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11 September 2015A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales

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Abstract

The Caryophyllales constitute a major lineage of flowering plants with approximately 12500 species in 39 families. A taxonomic backbone at the genus level is provided that reflects the current state of knowledge and accepts 749 genera for the order. A detailed review of the literature of the past two decades shows that enormous progress has been made in understanding overall phylogenetic relationships in Caryophyllales. The process of re-circumscribing families in order to be monophyletic appears to be largely complete and has led to the recognition of eight new families (Anacampserotaceae, Kewaceae, Limeaceae, Lophiocarpaceae, Macarthuriaceae, Microteaceae, Montiaceae and Talinaceae), while the phylogenetic evaluation of generic concepts is still well underway. As a result of this, the number of genera has increased by more than ten percent in comparison to the last complete treatments in the Families and genera of vascular plants” series. A checklist with all currently accepted genus names in Caryophyllales, as well as nomenclatural references, type names and synonymy is presented. Notes indicate how extensively the respective genera have been studied in a phylogenetic context. The most diverse families at the generic level are Cactaceae and Aizoaceae, but 28 families comprise only one to six genera. This synopsis represents a first step towards the aim of creating a global synthesis of the species diversity in the angiosperm order Caryophyllales integrating the work of numerous specialists around the world.

Introduction

Background

Recent years have yielded a wealth of new informatics tools and infrastructures to facilitate working with taxonomic data. Searching and accessing the necessary literature and type specimens has become much faster and easier, thus stimulating research in plant systematics. Modern monographic work synthesizes knowledge on a group of organisms and generates, manages, and publishes high quality data as needed for a variety of applications. To be biologically meaningful and to allow correct identification especially at the species level, the entities recognized such as species or genera should as much as possible reflect the latest understanding provided by phylogenetic and evolutionary approaches (Marhold & al. 2013; Borsch & al. 2015; Naciri & Linder 2015). In order to achieve this, an integration of the ever-increasing number of phylogenetic and evolutionary studies and the data generated by them with formal monographic work is imperative. This requires the research process to be organized in a way that explicitly links data on characters and specimens with evolutionary results and taxon concepts, and that allows for continuous updating to reflect the continuous generation of knowledge (Borsch & al. 2015). At the same time there is now an increased awareness for the need of a comprehensive assessment of the species diversity on our planet as a basis for conservation and sustainable use (Lughada & Miller 2009; Paton 2009; Hendry & al. 2010).

The Caryophyllales Global Synthesis Initiative

We have started a joint initiative entitled “Global synthesis of species diversity in the angiosperm order Caryophyllales”. The idea was to develop a practical model for integrative monographic work that is based on a sizable group of world-wide occurring organisms. Our approach is to develop a network and an internet portal based on a collaborative approach of institutions and individual researchers studying various aspects of the diversity and evolution of the Caryophyllales. Major partners will function as focal points with a long-term institutional commitment that ensures sustainability of the initiative. At the moment the core partnership consists of: the Instituto de Biología, Universidad Nacional Autónoma de México — UNAM (Mexico); the Instituto de Botánica Darwinion (Argentina); and the Botanic Garden and Botanical Museum Berlin — BGBM (Germany). The BGBM is committed to support the coordination of the initiative and will provide the biodiversity informatics infrastructure. Apart from aiming at satisfying the general scientific and applied need for quality data, we specifically envision the application of the Synthesis in the context of plant conservation. One of the immediate outputs of the Caryophyllales synthesis will be an up-todate taxonomic backbone for the World Flora Online as called for by the Convention on Biological Diversity's Conference of the Parties (2012). Considering the enormous progress on understanding and describing Caryophyllales diversity that has been made in the past two decades and will continue into the future, and also the need to have full coverage of the diversity for the users, the approach will entail a mechanism to integrate new results as they become available (Borsch & al. 2015) and therefore to present the best possible treatment for any given taxon. A comprehensive review and treatment at the generic level is an important step that will then be extended to the species level and be complemented by descriptive and other information.

The Caryophyllales are of great ecological and evolutionary interest because they show multiple origins of specialized morphological, anatomical, and biochemical traits. The order for example comprises the highest diversity of species with C4 photosynthesis after the grasses (Sage & al. 2011). Several lineages are highly specialized with adaptations to extreme habitats such as xeric conditions, salinity, or nitrogen-poor soils, and thus the group includes many succulent, halophytic, gypsophilous and carnivorous plants. The Caryophyllales are the order with the highest number of halophytes containing more than 21 % of all halophytic species (Flowers & al. 2010) and with the evolutionary oldest halophyte lineages (e.g. Kadereit & al. 2012a). The anatomy of Caryophyllales is also interesting because there are many wood features that are difficult to interpret (e.g. successive cambia, vessel elements perforation plates, ray anatomy, and raylessness; Carlquist 2010). In several families, pollen has evolved complex architectures and ultrastructures, based on the tricolpate pollen of the eudicots (Skvaria & Nowicke 1976; Nowicke 1994) with several Amaranthaceae exhibiting strongly derived metareticulate pollen with the highest number of apertures known in angiosperms (Borsch 1998; Borsch & Barthlott 1998). Caryophyllales are characterized by a unique phenomenon of petal loss and repeated reinvention (Brockington & al. 2012; Ronse De Craene 2013).

Furthermore, the order is relevant in the context of the Global Strategy for Plant Conservation and CITES by including groups of plants with many endangered species (e.g. Hunt 1999), most importantly Cactaceae,Droseraceae and Nepenthaceae. Species of economic importance include cereals and green vegetables (e.g. amaranth, quinoa, spinach, sugar beet), ornamentals (e.g. many Cactaceae and Caryophyllaceae species, carnivorous groups), noxious weeds (e.g. Alternanthera philoxeroides (Mart.) Griseb., Amaranthus spinosus L. and Mirabilis and Opuntia species), and of medical importance (mainly allergens; e.g. Amaranthus retroflexus L., Atriplex species, Kali turgidum (Dumort.) Guterm.).

Circumscription and phylogenetic relationships of Caryophyllales

For many decades the order just included the taxa characterized by a free central placentation (= Centrospermae), perisperm and curved embryos (Bittrich 1993a). Based on phylogenetic analyses, the Caryophyllales are now understood in a wider sense as also including Polygonales,Nepenthales and smaller lineages that were distantly placed in earlier classification systems, such as Rhabdodendron or Simmondsia (APG 1998; Cuénoud & al. 2002). This concept of the order is also basically followed here. We will summarize the changes in the classification of Caryophyllales and the different families below. This will help to understand the changes during the long transition phase from pre-cladistic to phylogeny-based taxonomy.

Several pre-cladistic classification systems were proposed for the Caryophyllales (for a review until the 1990s see Cronquist & Thorne 1994). Rodman & al. (1984) were the first to evaluate the classification of Caryophyllales based on a cladistic analysis of morphological characters. They reasserted the monophyly of the group and produced one of the first classifications based on a phylogenetic hypothesis (Table 1), even though this study was questioned with respect to its methodology and character selection (Gianassi & al. 1992). Subsequently, early molecular systematic studies (i.e. Rettig & al. 1992; Downie & Palmer 1994; Downie & al. 1997; Lledó & al. 1998) indicated the close relationship of the members of subclass Caryophyllidae (i.e. Caryophyllales, Plumbaginales and Polygonales sensu Cronquist 1981). Further studies (e.g. Albert & al. 1992; Chase & al. 1993) showed close phylogenetic relationships of Caryophyllidae with the carnivorous lineages Droseraceae and Nepenthaceae (Nepenthales sensu Cronquist 1981). Morton & al. (1997) found that the Madagascan Asteropeiaceae (Theales sensu Takhtajan 1987) and Physenaceae (described by Takhtajan 1985, but placed in Sapindales) both belong to Caryophyllales. This placement of Asteropeiaceae was further supported by a morphological cladistic analysis (Luna & Ochoterena 2004). Other studies (e.g. Fay & al. 1997) clarified the placement of Rhabdodendraceae (Rosales sensu Cronquist 1981), Simmondsiaceae (previously placed in either Euphorbiaceae or Buxaceae; Tobe & al. 1992), Tamaricaceae and Frankeniaceae (Violales sensu Cronquist 1988). The suggested affinities of all these groups to Caryophyllales were examined by Nandi & al. (1998), with respect to the fit of morphological characters, who adopted the concept of “caryophyllids s.l.” for a clade including Caryophyllales sensu Cronquist (1981) plus most of the taxa mentioned above. Nandi & al. (1998) further showed that the Dioncophyllaceae (Theaneae sensu Takhtajan 1987) and Ancistrocladaceae (Theales sensu Cronquist 1981) also belong to the carnivorous clade within the caryophyllids.

Based on a review of published molecular phylogenetic studies, the Angiosperm Phylogeny Group (APG 1998) considered 26 families to constitute the Caryophyllales with an expanded taxon concept. In this concept the order included all the families of the caryophyllids s.l. (Nandi & al. 1998) plus several family segregates such as Achatocarpaceae and Stegnospermataceae (segregated from Phytolaccaceae), Drosophyllaceae (segregated from Droseraceae) and Sarcobataceae (segregated from Chenopodiaceae). A molecular study by Savolainen & al. (2000) tested this circumscription and retrieved a well-supported clade. On their trees the authors annotated the families Halophytaceae (segregated from Chenopodiaceae) and Petiveriaceae (segregated from Phytolaccaceae).

Since then, further studies have improved the understanding of the phylogenetic relationships within the expanded Caryophyllales. The study by Cuénoud & al. (2002) based on 18S rDNA, rbcL, atpB, and partial matK sequences, was relevant in terms of its sampling, which included most of the families treated by Kubitzki & al. (1993) and Mabberley (1997), including Agdestidaceae,Barbeuiaceae and Gisekiaceae (segregated from Phytolaccaceae). Cuénoud & al. (2002) retrieved a well-supported Caryophyllales clade in most of their analyses, and one of their most relevant results was the detection of major subclades: the “core Caryophyllales” and “non-core Caryophyllales”. The core Caryophyllales included the traditionally recognized Caryophyllales (Cronquist 1981) and their segregated families; within this clade two subclades were recovered, one is the “lower core Caryophyllales” including Achat ocarpaceae,Amaranthaceae s.l. (including Chenopodiaceae), Asteropeiaceae and Caryophyllaceae, and the other is the “higher core Caryophyllales” including the rest of the traditional Caryophyllales and their segregated families. Within the “higher core Caryophyllales”, Corbichonia and Lophiocarpus (rbcL+matK analysis) were considered as separate linages within Molluginaceae and Phytolaccaceae, respectively. The “non-core Caryophyllales” clade also included two major subclades: one including Frankeniaceae, Plumbaginaceae, Polygonaceae and Tamaricaceae, and the other consisting of the carnivorous families Ancistrocladaceae, Dioncophyllaceae,Droseraceae and Nepenthaceae. The analysis of Cuénoud & al. (2002) resulted in inconclusive positions for Rhabdodendraceae and Simmondsiaceae. In their combined tree, Rhabdodendraceae were recovered as sister to all Caryophyllales (100 % Bootstrap; BS), and Simmondsiaceae as sister to the core Caryophyllales (moderate BS), while in the analysis of matK (low BS), both taxa as sisters were recovered as sister to the core Caryophyllales.

The study by Hilu & al. (2003) based on matK also retrieved two moderately supported major clades: “Caryophyllales I” and “Caryophyllales II”, the former including the core Caryophyllales plus Simmondsiaceae and Rhabdodendraceae (expanded core Caryophyllales). Within this clade two sister groups were recovered, “higher core I” and “higher core II”, one comprising Aizoaceae, Nyctaginaceae and relatives and the other Cactaceae, Portulacaceae, and relatives. The “Caryophyllales II” corresponded to the non-core Caryophyllales of Cuénoud & al. (2002).

Schäferhoff & al. (2009) employed sequence data of the petD group II intron and matK and recovered the “caryophyllids” and “polygonids” as major clades with high confidence. The caryophyllids include the expanded core Caryophyllales, which in general correspond to the “Caryophyllales I” of Hilu & al. (2003). The polygonids correspond to the non-core Caryophyllales of Cuénoud & al. (2002) and Caryophyllales II of Hilu & al. (2003). Furthermore, Schäferhoff & al. (2009) described the Microteaceae (segregated from Phytolaccaceae) with the sole genus Microtea, which they sampled for the first time in any molecular study. The study underscored the importance of a representative taxon sampling because Microtea was identified based on just two markers as an isolated lineage that together with the Simmondsiaceae is the successive sister to the rest of the caryophyllids.

Other recent authors mainly increased the number of characters analysed from the chloroplast. Brockington & al. (2009) using nine plastid genes from the singlecopy region, the inverted repeat, and two nuclear genes, recovered the non-core Caryophyllales and core Caryophyllales clades with Rhabdodendraceae followed by Simmondsiaceae plus the clade Asteropeiaceae—Physenaceae as successive sisters of the rest of the core Caryophyllales. Within the core Caryophyllales, the authors designated the “globular inclusion” clade as the clade that corresponds to the higher core Caryophyllales” of Cuénoud & al. (2002). Within this clade, they referred to the clade containing Cactaceae, Portulacaceae, and relatives as the “portulacaceous cohort” (an earlier-suggested name by Rodman & al. 1984, “cohort Portulacares”) and the lineage including Aizoaceae, Nyctaginaceae, and most parts of Phytolaccaceae possessing raphides as the “raphideclade”.soltis& al. (2011) used 17 genes (representing the three plant genomes) and came to results very similar to those of Schäferhoff & al. (2009) and Brockington & al. (2009).

Several phylogenetic studies have focused on the Portulacineae (= Cactineae/Portulacaceous cohort) (Applequist & Wallace 2001; Nylfeler 2007; Nylfeler & al. 2008; Ocampo & Columbus 2010). The most recent study by Nyffeler & Eggli (2010a) resulted in the disintegration of Portulacaceae, recognizing eight monophyletic families including the newly described Anacampserotaceae (segregated from Portulacaceae), the concept of Portulacaceae s.str. as a monotypic family, changes of the circumscription of some families (Didiereaceae), and the re-establishment and change of concept of others (Montiaceae and Talinaceae).

In summary, our concept of Caryophyllales includes 39 families (Fig. 1; Table 1, 2). It is in line with the families recognized by the APG III (2009) and Stevens (2001 onwards) but separates Agdestidaceae from Phytolaccaceae and Chenopodiaceae from Amaranthaceae and is updated by adding Kewaceae and Macarthuriaceae. In APG III (2009) Agdestis was included within Agdestidoideae (Phytolaccaceae) although its position as sister of Sarcobataceae obtained by Cuénoud & al. (2002) and Schäferhoff & al. (2009) supports the acceptance of the family described by Nakai (1942). APG III (2009) also recognized the Sarcobataceae. The Amaranthaceae are treated in a very wide sense in APG III (2009) including all Chenopodiaceae, merely reflecting that the two families form a monophyletic group (Cuénoud & al. 2002; Kadereit & al. 2003; Müller & Borsch 2005a), while the relationships of the major groups of Chenopodiaceae are still under debate. In this case, a merger resulting in a shift of family assignment for a major lineage of plants with many genera appearing in numerous studies in ecology, agriculture, and conservation had been promoted without robust phylogenetic data (see also respective family treatments).

Fig. 1.

Summary of the current knowledge on phylogenetic relationships in the Caryophy11ales. Based on Cúenod & al. (2002), Brockington & al. (2009) and Schäferhoff & al. (2009). Branch widths shown as triangles indicate species richness in these clades. — ••• = high support (95-100 BS/JK/PP), •• = medium support (75-94 BS/JK/PP), • = low support (50-74 BS/JK/PP).

Table 1.

Circumscription of Caryophyllales in a phylogenetic context according to different authors. The names in bold represent changes in comparison to the previous concept. * = not at family level in APG; ** = different concept from APG III (2009) and Stevens (2001 onwards).

Table 2.

Comparison of the current treatment with the two volumes edited by Kubitzki & al. (1993) and Kubitzki & Bayer (2003) representing the so far most inclusive generic treatment of the Caryophyllales.

For ease of recognition, we distinguish the two major Caryophyllales clades as caryophyllids and polygonids following Schäferhoff & al. (2009). The caryophyllids are the larger clade and include Simmondsiaceae and/ or Rhabdodendraceae along with the core Caryophyllales (= Centrospermae). The polygonids include the “carnivorous clade” with Ancistrocladaceae,Dioncophyllaceae,Droseraceae,Drosophyllaceae and Nepenthaceae plus the Frankeniaceae + Tamaricaceae and Plumbaginaceae + Polygonaceae subclades (Fig. 1)

Rationale for a revised generic classification

More than twenty years have passed since the publication of the comprehensive treatment of the centrospermous families of Caryophyllales by several authors in “Families and genera of vascular plants” (Kubitzki & al. [eds.] 1993). There, 15 families are recognized in the order (Achatocarpaceae,Aizoaceae,Amaranthaceae,Basellaceae,Cactaceae,Caryophyllaceae,Chenopodiaceae,Didiereaceae,Halophytaceae,Hectorellaceae,Molluginaceae,Nyctaginaceae,Phytolaccaceae,Portulacaceae and Stegnospermaceae [= Stegnospermataceae]). Ten years later the treatment was completed with the publication by Kubitzki & Bayer (2003), where the concept of “expanded Caryophyllales” was adopted, by now also treating Ancistrocladaceae,Asteropeiaceae,Dioncophyllaceae,Droseraceae,Drosophyllaceae, Frankeniaceae,Nepenthaceae,Physenaceae,Rhabdodendraceae,Simmondsiaceae, and Tamaricaceae. In addition to the treatments of these families, Cuénoud (2003) discussed the circumscription of the expanded Caryophyllales including Plumbaginaceae and Polygonaceae previously considered as separate orders by Kubitzki (1993b) and Brandbyge (1993), respectively. The two volumes edited by Kubitzki & al. (1993) and Kubitzki & Bayer (2003) represented the most inclusive generic treatment of the Caryophyllales with 675 genera in 27 families. In addition, there are even more comprehensive family-wide treatments including all genera and even species for the Aizoaceae (Hartmann & al. 2001a, b), Basellaceae (Eriksson 2007), Cactaceae (Hunt 2006) and Portulacaceae (Eggli 2002).

The new data also demonstrate that developing a classification system for the order is a dynamic process. An updated backbone at the generic level serves to present the current state of knowledge. We believe that this is an important step because many projects or researchers are specifically dealing with certain genera. Building upon a generic-level backbone will increase the efficiency of implementing the next steps towards a synopsis at species level. For example, Oxelman & al. (2013) keep a dynamically updated classification of Sileneae online. The long-term aim is to provide a portal where taxonomic, chorologic, nomenclatural, and phylogenetic information can be retrieved, along with literature, DNA sequences and images. This resource can be a valuable subproject for infrageneric and species-level taxonomy, and also for various other biological research projects where there is a strong need for a solid taxonomy based on phylogenetic relationships in Sileneae (e.g. Bernasconi & al. 2009). Such initiatives will be strongly supported by the Caryophyllales network, also by providing a sustained informatics infrastructure and a joint concept for future monographic work (Borsch & al. 2015). The published treatment of the genera of Caryophyllales, produced directly from an EDIT-Platform database, will provide a stepping stone for further refinement, also to encourage further research and participation in the network. Members of the Caryophyllales network will be able to correct and add to the information presented as it is databased. Once published, the continuously updated dynamic treatment will also be available as a freely accessible online data portal ( http://caryophyllales.org/).

Author names are abbreviated in conformity with Brummitt & Powell (1992) and its updates online; titles of serials in the nomenclatural reference citations are abbreviated in conformity with Bridson & al. (2004) and the titles of monographs are abbreviated in conformity with Stafleu & Cowan (1976–1988) and their successors, except that all components start with capital letters.

The name of the type species follows NCU-3 (Greuter & al. 1993); for genera not treated there, the names were obtained from reviewing protologues, Index Nominum Geneticorum (ING; Farr & Zijlstra 1996+), Tropicos (undated), or The International Plant Names Index (IPNI 2004+). To denote the taxon concept followed in the present publication, a “sec.” (secundum, following, according to; Stearn 1992) reference is given (see, e.g., Berendsohn 1997; Franz & Cardona-Duque 2013). This is a bibliographic citation of a (recent) paper or work giving the circumscription of the taxon (by means of a description, synonymy and/or details of the relationship to other taxa). In some cases, this is further discussed in a note, particularly with reference to the authors mentioned in the previous paragraph and later publications. The text of the following section, Classification, consists of direct output from the EDIT-Platform database.

Classification

The families and genera are listed in alphabetical order, with a single incertae sedis genus at the very end of the list. Each accepted name is given in bold and includes the standardized information mentioned above. The homotypic and heterotypic synonyms are listed according to the conventions in Willdenowia. Many names are followed by notes as mentioned above.

A small family comprising two genera and 16 species occurring in tropical America, from southeastern United States to South America (Medina 2009). Traditionally, the family has been included in Phytolaccaceae s.l., but its position as an independent lineage has been well supported by several molecular phylogenetic studies (Hilu & al. 2003; Schäferhoff & al. 2009; Brockington & al. 2009, 2011), which also showed that the family is more closely related to the Amaranthaceae/Chenopodiaceae clade rather than to Phytolaccaceae. Achatocarpaceae are characterized by having unisexual flowers, the gynoecium with two connate carpels, unilocular ovaries with two styles and a single ovule, berrylike fruits and pollen with obscure pores (Martinez-García 1985; Lipscomb 2003).

A monotypic family distributed from southern United States to Nicaragua (Rohwer 1993a), introduced and naturalized in Florida and the Antilles and cultivated as ornamentals in South America (Rzedowski & Calderón 2000). Traditionally, Agdestis was placed in Phytolaccaceae, subfamily Agdestioideae (e.g. Rohwer 1993a; Stevens 2001 onwards; Nienaber & Thieret 2003), but several molecular phylogenetic studies have shown that it represents a wellsupported independent lineage (Cuénoud & al. 2002; Hilu & al. 2003; Schäferhoff & al. 2009). These studies also showed a close but only moderately supported relationship of the family with Sarcobataceae. Agdestidaceae are climbers and characterized by paniculate inflorescences, semi-inferior ovaries and cypselas crowned by winglike sepals (Nienaber & Thieret 2003).

The Aizoaceae have a worldwide distribution throughout the tropics and subtropics (Hartmann 2001a, b). However, the centres of diversity are in the southwestern part of Africa (Bittrich 1986; Jürgens 1986; Hartmann 1991). Relatively few genera occur outside of southern Africa, mainly those from subfamilies Aizooideae,Sesuvioideae and Tetragonioideae. In contrast, Mesembryanthemoideae and Ruschioideae are largely restricted to southern Africa with few species found outside of this area (e.g. Mesembryanthemum crystallinum L., M. nodiflorum L. and Carpobrotus, Delosperma, Disphyma and Sarcozona species) (Hartmann 2001a, b). The family consists predominantly of succulent (mostly leaf succulent), annual to perennial herbs, subshrubs or shrubs, with undifferentiated perianth or biseriate with petals of staminodial origin, with mostly hygrochastic loculicidal fruits.

The Aloinopsis clade includes several small genera (ranging from one to six species), i.e. Aloinopsis,Deilanthe, Nananthus, Pleiospilos, Prepodesma,Rabiea and Tanquana (Klak & al. 2013). The group is found outside the winter-rainfall region of South Africa. The status and generic placement of numerous species in this group has been subject to many changes. For example, the monotypic Prepodesma has been included in five different genera by different taxonomic treatments. Aloinopsis, Nananthus and Rabiea are particularly poorly known in terms of species delimitation.

A large genus of 96 species, which has never been revised. Most species were previously placed in Ruschia, but separated from the latter based on fruit characters. Hartmann (2001a) recognized five subgenera within Antimima, but did not indicate which species belong to which subgenus. The molecular study by Klak & al. (2013) suggests that Antimima is not monophyletic in its current circumscription. A detailed morphological and molecular study is needed to establish generic boundaries within the Antimima clade, in which several other smaller genera such as Brausia, Hammeria, Smicrostigma and Zeuktophyllum take part (Klak & al. 2013).

A mysterious genus including three species. These were described by Haworth between 1795 and 1812. However, for two of the names no types have been selected yet, whereas for the third a drawing by Duncansan serves as a lectotype (Hartmann 2001a). The distribution of the genus is uncertain.

Cheiridopsis was found to be closely related to Ihlenfeldtia and Odontophorus (Klak & al. 2013). In addition, one of the three subgenera of Cheiridopsis,C. subg. Odontophoroides, could be more closely related to Odontophorus than to the remainder of Cheiridopsis (Hartmann 2001b). Although Cheiridopsis and Odontophorus were revised at species level (Hartmann 1976; Hartmann & Dehn 1987), their generic limits need to be reinvestigated.

A monotypic genus; its only species was already known to Linnaeus as Mesembryanthemum serratum L. The area where it was previously recorded has been subject to extensive cultivation, so the species had been thought to be extinct. However, it was rediscovered in 2007 and is currently considered as critically endangered (Klak & Low 2007). The hypanthium found in the flowers suggests a close relationship with Erepsia, where this species had been included previously (as E. serrata (L.) L. Bolus).

The genus includes eight species and is endemic to the Eastern Cape, South Africa. Its phylogenetic position near Delosperma has been confirmed (Klak & al. 2013), but the genus lacks a taxonomic revision.

A large genus of 142 species, which has never been revised. The study by Klak & al. (2013) suggests that Delosperma is not monophyletic in its current circumscription. A detailed morphological and molecular study is needed to establish generic boundaries within the Delosperma clade, in which several other smaller genera, including Corpuscularia, Ectotropis,Frithia, Mestoklema and Trichidiadema take part (Klak & al. 2013).

A large genus of 107 species, which has only partly been revised. With the exception of few misplaced species, the genus is thought to be monophyletic (Klak & al. 2003b; Klak & al. 2013). Hartmann (2007) recognized eight subgenera in Drosanthemum and also provided a key to the subgenera with a list of species included for each of them. Although also distribution maps were included for all eight subgenera, no vouchers were cited (Hartmann 2007), so that it remains uncertain on which material the maps were based. In addition, only one of the eight subgenera has so far been revised in part (Hartmann 2008). Since many species are threatened by agriculture or urban expansion, the genus is in urgent need of revision.

Eberlanzia includes eight species (Hartmann 2001a). However, the two species sampled by Klak & al. (2013) do not group together, suggesting that the genus is not monophyletic in its current circumscription.

The monotypic Muiria was placed in Gibbaeum, as G. hortenseae (N. E. Br.) Thiede & Klak, sec. Goldblatt & Manning (2000). The species was confirmed to be closely related to Gibbaeum, but its relationship to other species in the genus remains unresolved (Klak & al. 2013).

Hammeria Burgoyne in Cact. Succ. J. (Los Angeles) 70(4): 204. 1998 sec. Hartmann (2001b). — Type: Hammeria salteri (L. Bolus) Burgoyne A small genus consisting of only three species. The two species included in the molecular study by Klak & al. (2013) were not resolved as sisters. However, they were shown to group with other small genera such as Braunsia and Esterhuysenia in the Antimima clade (Klak & al. 2013).

Hereroa includes 27 species but lacks a taxonomic revision. The study by Klak & al. (2013) reveals Rhombophyllum (five species) and Bergeranthus (ten species) as its closest relatives. Denser sampling may in addition show that Hereroa is not monophyletic, with Rhombophyllum likely to be nested within it. On account of the close morphological resemblance between these genera, generic limits need to be critically reinvestigated.

The two species currently included in Ihlenfeldtia were previously included in Cheiridopsis. However,
the two species were moved each into their own genus and thought to be closely related to Tanquana (three species) and Vanheerdia (two species), based on characters of the fruits (Hartmann 1992). However Klak & al. (2013) confirmed the previous position of Ihlenfeldtia as a close relative of Cheiridopsis, which is supported by characteristics of the leaves (Hartmann 1992). See further notes under Cheiridopsis.

= Mesembryanthus Necker ex Rothm. in Notizbl. Bot. Gart. Berlin-Dahlem 15: 413. 1941, nom. inval. Lampranthus is a large genus of 194 species, which has never been revised. A molecular study of the Lampranthus group identified a core of closely related species, which makes up the current genus (Klak & al. 2003a). Groups of species not closely related to Lampranthus s.str. were placed in other genera, with some placed in new genera (Klak 2005).

A monotypic genus, which was shown to be sister to Dinteranthus (Klak & al. 2013), where it had been placed previously. The two genera form a clade together with Lithops and Schwantesia (Klak & al. 2013).

Lithops is one of the best-known genera among collectors of succulents. Species and subspecies are largely distinguished by the colour and markings present on the flattened leaf tops. The genus was shown to be closely related to Dinteranthus, Lapidaria and Schwantesia by Klak & al. (2013). In view of the close morphological resemblance between the four genera in terms of fruit and floral characters, it needs to be reinvestigated whether all of the genera should be maintained.

The genus includes 16 species, but lacks a taxonomic revision. Since the group is rather homogenous, further sampling is likely to confirm the monophyly of the genus with the species currently included. Marlothistella Schwantes in Gartenwelt 32: 599. 1928 sec. Hartmann (2001b). — Type: Marlothistella uniondalensis Schwantes

A new infrageneric classification has been proposed by Klak & Bruyns (2013). A broad generic circumscription for Mesembryanthemum has been reaffirmed and Mesembryanthemum subdivided into five subgenera, with all five shown to be monophyletic. Two species were recently reinstated and shown to form part of subgenus Volkeranthus, which is sister to the remainder of Mesembryanthemum (Klak & al. 2014). Thus, Mesembryanthemum currently includes 105 species.

Octopoma has been recognized by several authors (Hartmann 2001b) and Klak & al. (2013). However, the two infrageneric groups distinguished on account of differences in fruit morphology (Hartmann 2001b) were not confirmed by Klak & al. (2013).

A small genus including only two species. It is closely allied to Schlechteranthus (Klak & al. 2013), which also only incorporates two species. As indicated by the molecular analysis by Klak & al. (2013), the generic limits need to be critically reinvestigated.

A large genus including 206 species, for which no taxonomic revision has been compiled. Dehn (1993) recognized nine subgenera, of which only one has been studied further, Ruschia subg. Spinosae (Salm-Dyck) Dehn (Hartmann & Stüber 1993). However, it has since been established that Ruschia is not monophyletic in its current circumscription (Klak & al. 2013). The clade in which species of Ruschia s.str. are found is still poorly resolved, so that relationships of species groups of current Ruschia remain uncertain. In addition, much denser sampling is required to establish monophyly and relationships of the subgenera of Ruschia and their relationship to other members of the xeromorphic winter-rainfall clade (Klak & al. 2013).

Schlechteranthus Schwantes in Monatsschr. Deutsch. Kakteen-Ges. 1: 16. 1929 sec. Hartmann (2001b). — Type: Schlechteranthus maximiliani Schwantes A small genus of two species, which is endemic to Namaqualand. See further remarks under Polymita.

Scopelogena L. Bolus in J. S. African Bot. 28: 9. 1962 sec. Hartmann (2001b). — Type: Scopelogena verruculata (L.) L. Bolus A small genus with two species, which was placed in a clade with two species of the polyphyletic Ruschia (Klak & al. 2013). A comprehensive revision of Ruschia should therefore also address the generic delimitation of Scopelogena.

= Psammanthe Hance in Ann. Bot. Syst. 2: 659. 1851. The genus includes about 15 species; the exact number, however, is unknown and a taxonomic treatment is needed. Sesuvium contains an African clade consisting of C4 species and an American clade consisting of Cypselea (also C4) and a C3Sesuvium clade (Bohley & al. 2015). Sesuvium portulacastrum (L.) L., which belongs to the American clade, is found along tropical and subtropical coasts.

Skiatophytum forms part of the tribe Apatesieae, which consists of only 11 species. The tribe is considered to be monophyletic (Ihlenfeldt & Gerbaulet 1990; Klak & al. 2003b; Klak & al. 2015). Skiatophytum includes only three species, which are endemic to the south-western Cape region of South Africa (Klak & al. 2015). Based on a recent phylogenetic study, Klak & al. (2015) proposed that the monotypic Caryotophora Leistner should be considered part of Skiatophytum. In addition, it was shown that the lectotype and protologue of Mesembryanthemum flaccidum Jacq. did not correspond to the species currently associated with this name, which was described as S.flaccidifolium Klak (Klak & al. 2015). The type of the monotypic Saphesia, which is M. flaccidum, was found to be an insufficiently known species.

A monotypic genus, which was shown to be closely related to Zeuktophyllum (two species) and Octopoma p.p. (Klak & al. 2013). All three taxa are endemic to the Little Karoo, South Africa. The overall similarity between these taxa suggests that a broader generic concept should be adopted for this group of species.

= Ruschianthemum Friedrich in Mitt. Bot. Staatssamml. München 3: 563. 1960. Hartmann (2001b) treated Ruschianthemum as a distinct genus with R. gigas (Dinter) Friedrich as the only species. However, the species had already previously placed in Stoeberia because of strong similarities; it differs mostly in its fruit morphology, which has traditionally played an important role in delimiting genera in Aizoaceae. However, fruit characters have recently been shown to be far more homoplasious than previously expected (Klak & al. 2013), suggesting that fruit morphology on its own does not justify the recognition as a distinct genus. Given the large overall similarity in all other morphological characters to Stoeberia, this species has been reinstated as a member of Stoeberia by Chesselet & van Wyk (2002), based on very similar arguments.

Stomatium currently includes 39 species, but lacks a taxonomic revision. It was shown to be closely related to Chasmatophyllum (eight species), Mossia (one species), Neohenricia (two species), Peersia (three species) and Rhinephyllum (11 species) by Klak & al. (2013). Both Chasmatophyllum and Rhinephyllum also lack a taxonomic revision. All of these genera occur outside the winter-rainfall region of South Africa. The group shares a similar floral morphology, i.e. yellow or more rarely cream-coloured petaloid staminodes, absence of filamentous staminodes and a concavely shaped ovary wall. Over the past decades species have been shifted between genera since generic boundaries are poorly circumscribed.

Based on differences in fruit morphology, Hartmann & Liede (1986) excluded three species from Pleiospilos and established a new genus for them, Tanquana. However, its previously recognized close relationship to Pleiospilos was confirmed by Klak & al. (2013), and is also corroborated by leaf-morphological characters (Hartmann & Liede 1986).

The genus belongs to Sesuvioideae and comprises about 28 species in two monophyletic clades, T. subg. Trianthema and T. subg. Papularia (Bohley & al. 2015). The latter has been revised by Hartmann & al. (2011). Nearly all species are C4 plants: an exception is the C3 species T. ceratosepala Volkens & Irmsch.

Tribulocarpus belongs to the Sesuvioideae (Klak & al. 2003; Thulin & al. 2012) and is sister to the remaining genera of the subfamily, i.e. Sesuvium (incl. Cypselea), Trianthema and Zaleya. It is the only genus in the Sesuvioideae that includes only C3 species.

The genus includes 32 species and is divided into two subgenera (Hartmann & Niesler 2013). The latter study as well as earlier studies appear to be largely based on the types of Trichodiadema (Niesler 1997), since very little additional material (none from a South African herbarium) is cited as the basis for their taxonomic conclusions. Distribution ranges for the recognized species remain uncertain due to the lack of cited vouchers. In addition, monophyly of the genus needs to be reinvestigated in view its having been found nested among species of Delosperma (Klak & al. 2013).

= Rocama Forssk., Fl. Aegypt.-Arab.: 71. 1775. The genus is monophyletic and belongs to Sesuvioideae, where it is sister to Sesuvium (Bohley & al. 2015). Zaleya is a C4 genus and distributed in eastern Africa, southern Asia and Australia. It contains seven species (Hartmann 2011b).

Amaranthaceae Juss. sec. Müller & Borsch (2005).

Amaranthaceae belong to a clade together with Chenopodiaceae. Support for the monophyly of the “Amaranthaceae-Chenopodiaceae alliance” is found consistently in all molecular phylogenetic analyses (Manhart & Rettig 1994; Downie & al. 1997; Cuénoud & al. 2002; Kadereit & al. 2003; Müller & Borsch 2005a; Schäferhoff & al. 2009; Brockington & al. 2009). The family circumscription of the Amaranthaceae in the sense of Schinz (1893) was upheld by Townsend (1993) and confirmed as monophyletic with high statistical confidence by Kadereit & al. (2003) and Müller & Borsch (2005a). Following this concept the Amaranthaceae predominantly occur in tropical and subtropical regions with most of the species diversity in the Neotropics, eastern and southern Africa and Australia (Müller & Borsch 2005a, b; Sánchez-del Pino & al. 2009). Subfamily Gomphrenoideae has been revealed as monophyletic and nested within the Amaranthoideae and is characterized by unilocular anthers (Sánchez-del Pino & al. 2009) and metareticulate pollen (Borsch & Barthlott 1998; in core Gomphrenoideae except Irenella, Iresine and Woehleria). In contrast, subfamily Amaranthoideae is largely paraphyletic. The genera Bosea and Charpentiera were found as successive sisters to the remainder of the Amaranthaceae (Müller & Borsch 2005a). The Celosioideae (corresponding to the celosioid clade) are the only natural tribe in the pre-phylogenetic classification of the family and further major lineages are constituted by the amaranthoid clade (Amaranthus, Chamissoa and relatives), the aervoid clade (Aerva, Ptilotus and relatives) and the achyranthoid clade (Achyranthes, Centemposis, Cyathula, Pupalia, Sericocoma and many other African genera; Müller & Borsch 2005b). The Angiosperm Phylogeny Group (APG 1998) proposed to apply the name Amaranthaceae to the complete Amaranthaceae—Chenopodiaceae alliance, essentially adopting the family concept of Baillon (1887) and Mallingson (1922). The broad family circumscription was also adopted in subsequent versions of the APG classification (APG II 2003; APG III 2009). However, since recent phylogenetic analyses rather indicate the monophyly of the core Chenopodiaceae but are not yet conclusive about the position of the subfamily Polycnemoideae, the widely used family name Chenopodiaceae is maintained (see introduction to the family Chenopodiaceae). The four genera of the well-supported polycnemoid lineage (Hemichroa, Nitrophila, Polycnemum, Surreya) that corresponds to the subfamily Polycnemoideae share petaloid tepals, two large bracteoles supporting the flower, an androecium that is basally united into a tube and bilocular anthers with the Amaranthaceae sensu Schinz (1893), Masson & Kadereit (2013). We are therefore provisionally treating this subfamily under the Amaranthaceae along with Endlicher (1841), Moquin-Tandon (1849) and Scott (1977).

The genus may not be monophyletic and includes two principal lineages (Thiv & al. 2006). One of these was shown as sister to the remainder of the aervoid clade (represented by A. javanica Juss.; Müller & Borsch 2005a) and the other (represented by A. leucura Moq.; Müller & Borsch 2005b) as sister to Ptilotus. Further study of the aervoid clade is needed to clarify generic concepts.

The genus Alternanthera is well supported as monophyletic in the current circumscription and is characterized by the presence of capitate stigmas and in most species also distinct androecial appendages that alternate with the filaments. The previously recognized genera do not represent natural entities except Mogiphanes, which is nested within one of the two major subclades of Alternanthera (Sánchez-del Pino & al. 2012).

The genus is not monophyletic as currently circumscribed because its two species, Calicorema capitata and C. squarrosa (Schinz) Schinz, appear in two completely different lineages of the achyranthoid clade (Müller & Borsch 2005a, b). Correct generic assignment has to await a comprehensive analysis of the achyranthoid clade.

Celosieae. Dendroportulaca (formerly placed in Portulacaceae) has been shown to be referable to Deeringia and the only species, Dendroportulacamirabilis Eggli, has been transferred there (Apple-quist & Pratt 2005).

Monotypic and known from a single historical specimen (Pedersen 2000). Affinities are unclear but a placement within the gomphrenoid clade of Gomphrenoideae (Sánchez-del Pino & al. 2009) is certain, where it shares a pollen morphology similar to Pfaffia.

Polycnemoideae. Hemichroa consists of only one species; two further species have been segregated as Surreya (see there for details; Masson & Kadereit 2013). The succulent halophyte H. pentandra R. Br. is endemic to Australia. It is sister to Surreya (Masson & Kadereit 2013).

The genus is monophyletic (Sánchez-del Pino & al. 2009; Borsch, Flores Olvera, Zumaya & Müller, in review) with approximately 45 species all of which are characterized by Iresine-type pollen (Borsch 1998). The two species formerly classified as Dicraurus on the base of alternate and not opposite leaves are nested within the Iresine clade, confirming the merger by Henrickson & Sundberg (1986). Their dense indumentum with branched trichomes appears to be an adaptation to the dry habitats of northern Mexico.

Polycnemoideae. Nitrophila consists of four (to eight) species distributed in western North America and South America, and the genus represents a classical example of an amphitropical desert disjunction (Masson & Kadereit 2013). Nitrophila shows leaf anatomical adaptations to physiological drought.

The genus name was lectotypified by Standley (1917) using an Australian species, P. conicus R. Br. (≡ Gomphrenaconica (R. Br.) Spreng.). Palmer (1998) accepted G. conica along with the other Australian species of Gomphrena and indicated that this is a rare species that grows in sandy soils close to coasts. Considering this, Philoxerus would have to be a synonym of Gomphrena. The problem is that Hooker (1880, Genera plantarum) kept the genus name Philoxerus separate from Gomphrena and, rather than using morphological characters, applied a genus concept for Philoxerus to comprise Gomphrena species of coastal habitats in America, Africa and Australia. This is practically upheld in the genus concept of Biutaparon Raf. (Townsend 1993), with four coastal species, although Townsend did not even cite the name Philoxerus. Mears (1982a, b) argued that Philoxerus had been used for the American coastal species, so he actually looked for a name that would define a genus of coastal species based on the American coastal plants originally described by Linnaeus as G. vermicularis. What Mears overlooked is that G. conica also appears to be a coastal plant (Palmer 1998), so that Bentham's 1880 generic concept of a gomphrenoid genus of coastal plants under the name Philoxerus would actually have been correct with five and not four species. Strictly applying such a genus concept to formal nomenclature, Biutaparon is a synonym of Philoxerus. However, in the course of analysing evolutionary relationships it will have to be seen if the adaptation to coastal habitats correlates with other characters that could provide synapomorphies for circumscribing and maintaining a genus Philoxerus, and if these synapomorphies are shared by P. conicus and the other coastal species.

A well-circumscribed monophyletic genus with two species that was long treated as part of a widely circumscribed genus Gomphrena Mart, but resurrected by Pedersen (1990) because of its morphological distinctness (gamopetalous perianth, cauline leaves reduced to scales). Molecular phylogenetic analyses (Sage & al. 2007; Sánchez-del Pino & al. 2009) depicted Xerosiphon as an isolated lineage in the gomphrenoid clade of subfamily Gomphrenoideae.

A family with three genera and around 36 species mainly distributed in the southern and eastern parts of Africa, but also found in North America, South America, and Australia (Nyffeler & Eggli 2010a). The species of this family are traditionally considered members of Portulacaceae; however, molecular phylogenetic studies have shown that the traditional Portulacaceae are not monophyletic (Hershkovitz & Zimmer 1997; Applequist & Wallace 2001; Nyffeler 2007; Nyffeler & Eggli 2010a; Ocampo & Columbus 2010). Nyffeler & Eggli (2010a) proposed the segregation of the traditional Portulacaceae into four families (Anacampserotaceae, Montiaceae,Portulacaceae and Talinaceae) based on morphological and molecular data. In this context, the Anacampserotaceae are recognized by their capsules with loculicidal dehiscence, endocarp valves forming a basket-like structure and seeds with testa layers separate from each other (Nyffeler & Eggli 2010a).

Anacampseros with c. 34 herbaceous species distributed in Africa, Australia, North and South America, is the most diverse genus of Anacampserotaceae (Nyffeler & Eggli 2010a). Phylogenetic analyses recover this lineage as a derived monophyletic group with moderate statistical support (Nyffeler & Eggli 2010a).

A monogeneric family comprising 18 species with a disjunct paleotropical distribution in western and central Africa and southeastern Asia (Rischer & al. 2005). The family includes only non-carnivorous plants characterized by having nuts, ruminate endosperm and a gynoecium partly inferior with a single ovule (Heubl & al. 2006). Traditionally, the family was placed either in the order The ales (e.g. Thome 1992) or Dilleniales (e.g. Thorne 2000). However, the position of the family within Caryophyllales and its close relationship with the “partially carnivorous” Dioncophyllaceae (see there) was shown by the early molecular phylogenetic study of Nandi & al. (1998). These results were confirmed by subsequent studies (e.g. Meimberg & al. 2000; Cuénoud & al. 2002; Hilu & al. 2003; Brockington 2009, 2011; Schäferhoff & al. 2009; Renner & Specht 2011), which have also shown, with high support, that both Ancistrocladaceae and Dioncophyllaceae are part of the “carnivorous clade” of the Caryophyllales. Other studies focusing on the evolution of carnivory and relationships within this clade (e.g. Heubl & al. 2006; Renner & Specht 2011) suggest that the absence of carnivory in Ancistrocladaceae can be explained as a complete secondary loss of this character.

A monogeneric family with eight species endemic to Madagascar (Kubitzki 2003). The genus was traditionally placed in Theales, either in its own family (e.g. Takhtajan 1987; Thome 1992) or within Theaceae (e.g. Cronquist 1988). However, early molecular phylogenetic studies have shown the affinities of Asteropeiacae within Caryophyllales and the close relationship with Physenaceae (e.g. Morton & al. 1997). These results were confirmed by subsequent studies (e.g. Cuénoud & al. 2002; Brockington 2009, 2011; Soltis & al. 2011). The clade Asteropeiaceae—Physenaceae is also well supported by wood-anatomical characters (e.g. Miller & Dickison 1992; Dickison & Miller 1993; Carlquist 2006); some member species (with small circular alternate pits on vessels, vasicentric tracheids plus fibre tracheids, abaxial confluent diffuse parenchyma and predominantly uniseriate rays) have been proposed as synapomorphies to the family (e.g. Carlquist 2006).

A monotypic family restricted to Madagascar (Rohwer 1993). The family is characterized by ovaries consisting of two united carpels with two locules and by capsules (Rohwer 1993). Traditionally, the family was placed in Phytolaccaceae subfamily Barbeuioideae, but its position as an independent lineage has been supported by several molecular phylogenetic studies (Cuénoud & al. 2002; Hilu & al. 2003; Schäferhoff & al. 2009).

Basellaceae are a small tropical and subtropical family native to the Americas, southeastern Africa, Madagascar and possibly Asia. The centre of diversity is in the Andes of northwestern South America, but the centre of origin may very well be in Africa. At present, four genera (Anredera, Basella, Tournonia, Ullucus) with a total of 19 species are recognized, most of them succulent vines occurring in dry habitats. Some species are cultivated, and one (Ullucus tuberosus Caldas) is an important high-Andean crop grown for its edible tubers.

A monophyletic group of species in Anredera corresponds to the previously recognized taxon Tandonia, but a formal recognition of Tandonia would make the remaining Anredera paraphyletic (Eriksson 2007).

One species, B. paniculata Volkens, is morphologically deviating in Basella, and may be better placed in a genus of its own. A phylogenetic analysis based on morphological data gave inconclusive results regarding its placement (Eriksson 2007).

Cactaceae comprise about 120 to 130 genera and some 1450 to 1870 species (Hunt 2006; Nyffeler & Eggli 2010b). Most species are highly modified perennial stem succulents which conserve water to survive temporary dry periods. Only some two dozen species of the genera Pereskia, Pereskiopsis and Quiabentia have a shrubby or tree-like habit with more or less fleshy leaves. All species of the family bear characteristic spine clusters (i.e. areoles), representing short shoots with leaves transformed into spines already at the stage of primordia. Some taxa are spineless and even lack areoles at maturity but all species bear areoles as seedlings. This characteristic is a true synapomorphy of the entire family. Cacti are native to the Americas, except for the widely distributed Rhipsalis baccifera (Sol.) Steam that also occurs in tropical Africa, Madagascar, and on islands in the Indian Ocean. Several species from different lineages have been introduced worldwide as crop plants or ornamentals and have become naturalized, and are classified as invasive aliens in several areas, including Australia, southern Africa, and the Mediterranean. For a long time in the past, the classification into genera and suprageneric groups was based on form characteristics of vegetative and reproductive structures, culminating in the fine-grained classifications of Backeberg (1958–1962, 1966) or Buxbaum (1962) and Endler & Buxbaum (1974). Many of the highly modified structural features are associated with the succulent life strategy (e.g. Nyffeler & al. 2008), and hence provide particular challenges in the interpretation of a classification based on purported relationships. The consensus classification initiative as reported by Hunt & Taylor (1986) and subsequent papers helped to overcome the deviating systems used in the second part of the 20th century, but also fell short in not being based on further and expanded data sets of comparative data for reconstructing relative relationships. However, the molecular phylogenetic studies (see the introduction and Nyffeler & Eggli (2010b) provide the base for an increasingly stable backbone classification for major suprageneric clades. At the same time, unexpected novel placements are suggested by such studies for several species or genera, such as Blossfeldia (Nyffeler 2002) or Lymanbensonia (Korotkova & al. 2010), while long-established genera, such as Echinocactus and Ferocactus but also Mammillaria have been found to be polyphyletic (Bárcenas & al. 2011; Hernández-Hernández & al. 2011; Vázquez-Sánchez & al. 2013). To use these findings for updating the generic classification of the family is a pronounced challenge (Hunt 2006; Nyffeler & Eggli 2010b).

= Monvillea Britton & Rose, Cactaceae 2: 21. 1920. Currently accepted as monotypic with A.tetragonus (L.) Britton & Rose (Hunt 2006), whereas all other names suggested in this genus are of uncertain application or were wrongly assigned to Acanthocereus. The molecular phylogenetic study of Arias & al. (2005) showed that Acanthocereus would need to be expanded to include Peniocereus subg. Pseudoacanthocereus Sánchez-Mej., but no new combinations have yet been published.

= Trichopuntia Guiggi, Cactology 2(Suppl.): 2. 2011. Austrocylindropuntia as originally treated in Hunt (2006) was found as not monophyletic by Ritz & al. (2012). Austrocylindropuntia lagopus (K. Schum.) F. Ritter was found sister to the remaining species of Austrocylindropuntia and Cumulopuntia and was therefore segregated as a monotypic genus Punotia D. R. Hunt; see also there.

Borzicactus is reinstated based on the results of Schlumpberger & Renner (2012). Its circusmcription has been the subject of some debate, as summarized by Bregman (1992). The exact delimitation of Borzicactus and the genera currently included or considered related to it is still unclear.

Originally monotypic with B. brasiliensis. Majure & al. (2012) found good support for a sister-group relation of Opuntia schickendantzii F. A. C. Weber., and transferred this species to Brasiliopuntia.

= Winterocereus Backeb., Kakteenlexikon 455. 1966. The broad circumscription of Cleistocactus as employed by Anderson (2001, 2005), and Hunt (2006) goes back to the Cactaceae consensus classification reported by Hunt & Taylor (1986), where the predominantly ornithophilous floral syndrome was used as a diagnostic character. Schlumpberger & Renner (2012) found that Cleistocactus s.l. is polyphyletic — the monotypic Cephalocleistocactus was placed as sister to Yungasocereus, with Cleistocactus s.str. as sister to Vatricania next to Weberbauerocereus, and two terminals representing the former Borzicactus and Loxanthocereus were placed in the Oreocereus clade, the former next to Matucana and the latter next to Haageocereus. Deciding whether Cleistocactus s.l. should be retained or split up is difficult, since sampling of the group and its possible sister taxa is still inadequate. The affiliation of Loxanthocereus with Haageocereus was seen earlier, and Nyffeler & Eggli (2010b) listed it as synonym of Haageocereus.

Plastid and nuclear ITS data so far provided inconclusive results for the placement of Consolea and its separation from Opuntia. Consolea was found to be imbedded in Opuntia by Griffith & Porter (2009) based on combined nuclear and plastid data. The plastid and nuclear data of Majure & al. (2012) supported the monophyly but were incongruent regarding the placement of Consolea: while plastid data resolved Consolea outside of Opuntia (BS=53%), nuclear ITS data resolve Consolea within Opuntia (BS=75%), yet both these placements receive only weak support. Support for a placement outside of Opuntia increased to 81% BS when only diploids were included in a combined nuclear and plastid analysis. Majure & al. (2012) pointed out that evolution in Opuntia and allies involves hybridization and allopolyploidization and that Consolea might be of allopolyploid origin, as indicated by the incongruent plastid and nuclear trees. Nevertheless, Majure & al. (2012) argued for recognizing Consolea as a genus distinct from Opuntia because of good support for its monophyly, the placement by combined plastid and nuclear data outside of Opuntia and unique morphological characteristics.

= Escobrittonia Doweld in Sukkulenty 3: 17. 2000. Found as highly polyphyletic by Bárcenas & al. (2011), and as nested in Mammillaria. One core Coryphantha clade was resoved but only weakly supported as monophyletic (0.65 PP from Bayesian Inference). Vázquez-Sánchez & al. (2013) likewise found Coryphantha as polyphyletic, but not nested in Mammillaria; however, far fewer species were sampled therein. One maximally supported group was found that also contains Neolloydia matehualensis Backeb., while other Coryphantha species were found close to Echinomastus and Escobaria. As in the whole mammilloid clade, support for the relevant nodes is still weak and generic limits of Coryphantha need further evaluation. See also notes under Mammillaria and Neollydia. Recent traditional monograph by Dicht & Lüthy (2003).

Griffith & Porter (2009) found no support for a monophyletic Cumulopuntia, but it was also not contradicted. Cumulopuntia was then confirmed as monophyletic by Ritz & al. (2012). Cumulopuntia falls in two clades in the molecular phytogeny, one consisting of C. sphaerica (C. F. Först.) E. F. Anderson and related taxa from the W Andean slopes of Chile and Peru, characterized by forming dwarf shrubs with easily detachable stem segments, and another consisting of Cumulopuntia s.str., characterized by growth in often dense cushions, with firmly attached stem segments (Griffith & Porter 2009; Ritz & al. 2012). For the C. sphaerica clade, the generic name Sphaeropuntia was recently published, but its circumscription is not yet fully resolved, and it this thus better treated as synonym for the time being.

Griffith & Porter (2009) found no support for a monophyletic Cylindropuntia based on combined nuclear and plastid markers, while Bárcenas & al. (2011) found a monophyletic Cylindropuntia with high to maximal support based on plastid data only.

= Kroenleinia Lodé in Cact. Avent. Int. 102: 25. 2014. Echinocactus turns out to be paraphyletic in recent molecular studies (Bárcenas & al. 2011; Hernández-Hernández & al. 2011; Vázquez-Sánchez & al. 2013), with E. grusonii Hildm. resolved in a separate clade from the remaining four species, yet with only low support (Vázquez-Sánchez & al. 2013) or in a polytomy (Bárcenas & al. 2011). Vázquez-Sánchez & al. (2013) re-circumscribed Echinocactus to include only four species, excluding E. grusonii and also E. polycephalus Engelm. & J. M. Bigelow but did not suggest new generic assignment for these species. The generic name Kroenleinia was recently erected for E. grusonii, but it may be premature to accept this monotypic genus in view of the numerous unresolved or poorly supported topologies in the group.

Echinocereus was studied in detail and found as monophyletic by Sánchez & al. (2014) but excluding E. pensilis J. A. Purpus, which was resolved distant from Echinocereus and as as sister to the Stenocereus group. Because E. pensilis had been regregated as a monotypic genus Morangaya, its reinstatement was suggested by Sánchez & al. (2014).

= Leucostele Backeb. in Kakt. And. Sukk. 4: 1. 1953. The present wide circumscription of Echinopsis goes back to the mid-1970s. First indications that this broad Echinopsis is polyphyletic were found by Lendel & al. (2006) and Ritz & al. (2007), and Schlumpberger & Renner (2012) in their deeply sampled study indeed found vast polyphyly and paraphyly throughout most of the subtribe Trichocereinae. Species of Echinopsis were scattered over eight different clades and interspersed with species of Acanthocalycium, Arthrocereus, Borzicactus, Cephalocleistocactus, Cleistocactus, Denmoza, Espostoa, Haageocereus, Harrisia, Matucana, Mila, Oreocereus, Oroya, Pygmaeocereus, Rauhocereus, Samaipaticereus, Weberbauerocereus and Yungasocereus, all of which are part of a highly supported clade (100% BS). To transform their results into a formal classification of monophyletic genera is no easy task. It would entail either to further broaden an already very heterogeneous genus by including the genera mentioned above or to accept about a dozen segregates (valid generic names are at hand). Nevertheless, maintaining Echinopsis (sensu Hunt 2006) is rather not an option, as it is clearly polyphyletic and should be split up. The necessary new combinations are already available (Schlumpberger 2012); a fully revised generic circumscription is still to be published.

The diminutive Eriosyce laui Lüthy from northern Chile has been found to differ morphologically from the remaining taxa of Eriosyce s.l. by Nyffeler & Eggli (1997), and was subsequently segregated as the monotypic genus Rimacactus. As long as this segregation is not backed up by molecular data, it appears premature to accept the genus. Recent treatments by Kattermann (1994) and Hoffmann & Walter (2005; Chile).

Vázquez-Sánchez & al. (2013) found Ferocactus in its current circumscription to be vastly polyphyletic, and the same is true for F. sect. Bisnaga. The Ferocactus clade found by Vázquez-Sánchez & al. (2013) also includes the genera Glandulicactus, Leuchtenbergia, Stenocactus and Thelocactus, corroborating the results of a much less dense sampling by Hernández - Hernández & al. (2011). The Ferocactus clade is morphologically characterized by pericarpels with scales and ribbed stems, and Vázquez-Sánchez & al. (2013) suggested expanding Ferocactus to embrace the genera just mentioned as the best taxonomic solution to make Ferocactus monophyletic, yet Leuchtenbergia is the oldest name of this assemblage and would have priority, unless the name Ferocactus is conserved.

= Marenopuntia Backeb. in Desert Pl. Life 22: 27. 1950. Corynopuntia was included in Grusonia s.l. (Wallace & Dickie 2002; Anderson 2001, 2005; Nyffeler & Eggli 2010b), then accepted as separate genus by Hunt (2006). Griffith & Porter (2009) argued for recognizing Corynopuntia as a distinct genus, and Grusonia as monotypic, although support for the monophyly of Corynopuntia was only 67% BS in their study. Their data also suggest that Micropuntia could be recognized as a separate genus. Bárcenas & al. (2011) did not find support for treating Corynopuntia separately from Grusonia, and in addition found no support for a monophyletic Corynopuntia-, therefore, the circumscription of Corynopuntia still needs to be clarified.

Found as monophyletic at first by Ritz & al. (2007), then studied in more detail and confirmed as monophyletic by Meregalli & al. (2010). Demaio & al. (2011) conducted the most detailed phylogenetic study by sampling almost the whole genus and again confirmed the monophyly of Gymnocalycium with maximal support. Recent illustrated synopsis by Charles (2009).

Harrisia was confirmed as monophyletic by Franck (2012), with a revised infrageneric classification published shortly after (Franck & al. 2013a). The recently described genus Estevesia P. J. Braun was not included in any molecular study so far. It was provisionally placed in the synonymy of Harrisia by Nyffeler & Eggli (2010b). For synopsis see Franck (2012); further phylogenetic studies see Franck & al. (2013b).

The circumscription of Hatiora has been clarified recently. Hatiora including Rhipsalidopsis as adopted by Barthlott (1987), Barthlott & Hunt (1993), Barthlott & Taylor (1995), Hunt (2006) and Nyffeler & Eggli (2010b) was found to be polyphyletic (Calvente & al. 2011; Korotkova & al. 2011). Hatiora should therefore be restricted to species with cylindrical stems, terete pericarpels, and small yellow-orange or magenta flowers, corresponding to Hatiora in the traditional sense. Accordingly, Rhipsalidopsis in its traditional circumscription should again be accepted at generic rank.

= Wilmattea Britton & Rose, Cactaceae 2: 195. 1920. Hylocereus is morphologically very similar to Selenicereus, and available phylogenetic studies as well as morphological and anatomical data so far suggest that the two genera could be merged (Hernández-Hernández & al. 2011; Bárcenas & al. 2011, Gómez-Hinostrosa & al. 2014), but they still need to be studied more extensively before firm conclusions on their circumscription are possible.

In the second half of the 20th century, Lemaireocereus was referred to as a synonym of Pachycereus (see there) by Buxbaum (1961), Bravo-Hollis (1978), and Gibson & Horak (1978), based on similar floral morphology. Phylogenies based on molecular (Arias & al. 2003) and structural data (Arias & Terrazas 2006) consistently have revealed that Lemaireocereus is an early-diversified lineage within Pachycereinae. Lemaireocereus should be restricted to species with rounded ribs, terminal flowers with long hairs and bristles, fruit with irregular dehiscence, and red pulp (Arias & Terrazas 2009; Arias & al. 2012).

Several considerably different generic concepts have been suggested for Lepismium in the past 80 years. It was either recognized as monotypic for L. cruciforme (Vell.) Miq., e.g. by Britton & Rose (1923) or included into Rhipsalis (Schumann 1899; Vaupel 1925, 1926). Barthlott (1987) and Barthlott & Taylor (1995) redefined Lepismium based on the mesotonic branching as the main diagnostic character, but this circumscription was found to be polyphyletic by Nyffeler (2002) and Korotkova & al. (2010). Consequently, some of its species were transferred to Lymanbensonia and Pfeiffera by Korotkova & al. (2010). Recent monograph by Barthlott & Taylor (1995).

Lophocereus (including L. gates and L. schottii) was strongly recognized as a separate genus, restricted to the Sonoran Desert, by e.g. Lindsay (1963) and Bravo-Holis (1978). Comparative studies carried out by Gibson & Horak (1978) showed that those species share morphological and anatomical characteristics with Pachycereus marginatus (DC.) Britton & Rose. However, other taxonomists preferred to include this genus and others (e.g. Backebergia, Lemaireocereus, Marginatocereus, Mitrocereus, Pterocereus) in a broader genus Pachycereus (Barthlott & Hunt 1993; Hunt 2006). Phylogenetic studies based on structural (anatomy + morphology) and molecular data confirm that Lophocereus is monophyletic including three species (L. marginatus (DC.) S. Arias & Terrazas as sister to the remaining species). The genus represents a lineage within the subtribe Pachycereinae, but is not directly related to Pachycereus s.str. or Backebergia (see there; Hartmann S. & al. 2001, 2002; Arias & al. 2003; Arias & Terrazas 2006). A proposal to recognize this genus newly circumscribed (now going also beyond the Sonoran Desert) was conducted by Arias & al. (2012). Lophocereus now includes taxa characterized by cylindrical stems with basal branching, an apical fertile zone with areoles, and spines larger than those of the sterile zone, and two or more flowers per areole. The flowering zone is conspicuously modified in all three species, although in L. gatesii M. E. Jones and L. schottii internodes are shorter and spines are longer (Arias & Terrazas 2009; Arias & al. 2012). Structural changes in the fertile zone exist between several genera of Pachycereinae, including cephalium (e.g. Backebergia and Cephalocereus species), pseudocephalium (e.g. Lophocereus and Neobuxbaumia species) and intermediate forms. However, those structures are highly homoplastic and occur within several genera.

Butterworth & al. (2002) found L. williamsii as sister to Obregonia and L. diffusa (Croizat) Bravo as sister to Acharagma, yet both with only moderate support. In contrast, Lophophora williamsii and L. diffusa were resolved as sisters with moderate support in the study of Vázquez-Sánchez & al. (2013), who also found high support for the sister relationship of Lophophora and Obregonia, justifying generic rank for both.

= Acanthorhipsalis Kimnach in Cact. Succ. J. (Los Angeles) 55: 177. 1983, nom. illeg. Segregated from Acanthorhipsatis (Kimnach 1984), but otherwise either assigned to Lepismium (Barthlott 1987; Barthlott & Taylor 1995; Anderson 2001, 2005) or to Pfeiffera (Hunt 2006). The molecular phylogenetic study of Korotkova & al. (2010) unexpectedly found the three species now assigned to Lymanbensonia to represent a highly supported isolated clade distant from either Lepismium or Pfeiffera. As this new clade contained the nomenclatural type of Lymanbensonia, this generic name was reinstated.

Griffith & Porter (2009) found Maihueniopsis polyphyletic based on a combined analysis of nuclear ITS and plastid trnL-F, but Ritz & al. (2012) found a monophyletic Maihueniopsis to be strongly supported by nuclear phyC and plastid trnK/matK. The reasons for these deviating results are discussed in detail by Ritz & al. (2012) and appear to result from peculiarities in the evolution of the ITS sequences used by Griffith & Porter (2009) that seem unsuitable to adequately represent phylogenetic relationships.

= Escobariopsis Doweld in Sukkulenty 3: 23. 2000. Mammillaria is the largest genus within Cactaceae, and numerous suggestions for infrageneric entities have been proposed, often then segregated as different genera; the different taxonomic concepts were summarized by Butterworth & Wallace (2004). Although several phylogenetic studies dealing with the genus and allies have been published, there are still many uncertainties that result from insufficient phylogenetic resolution and support. Mammillaria was studied in detail using data from the plastid rpl16 intron and psbA-trnH intergenic spacer by Butterworth & Wallace (2004), who sampled c. 4/5 of the accepted species, and Bárcenas & al. (2011) for trnK/matK compiled an even more extensive sampling. Mammillaria was also included in the phylogenetic studies of the tribe Cacteae by Butterworth & al. (2002) and Vázquez-Sánchez & al. (2013), though with much fewer species sampled. The first sequence data already hinted at a non-monophyly of Mammillaria (Butterworth & al. 2002), yet without support. The results of Butterworth & Wallace (2004), based on a detailed sampling, again suggested polyphyly of Mammillaria. The genera Coryphantha, Escobaria, Mammilloydia, Neolloydia, Ortegocactus and Pelecyphora were found nested in a maximally supported Mammillaria s.l. clade. Bárcenas & al. (2011) did not find sufficient support for a monophyletic Mammillaria, and Coryphantha (likewise polyphyletic), Escobaria and Ortegocactus were nested in different Mammillaria clades. Vázquez-Sánchez & al. (2013) found that Coryphantha and Mammillaria could be separate clades, yet Mammillaria was supported as monophyletic only in the parsimony tree (61% BS/78% JK), but not found as monophyletic by Bayesian Inference. A clade of Coryphantha incl. Neolloydia was maximally supported in the parsimony and Bayesian trees, but C. macromeris (Engelm.) Lem. fell outside that clade, suggesting that Coryphantha is likewise polyphyletic. Escobaria was found polyphyletic as well (Vázquez-Sánchez & al. 2013), but only few species have been sampled. The results of Vázquez-Sánchez & al. (2013) also provided some insights into generic limits in the whole assemblage, as well as taxonomic changes by segregating Cochemiea from Mammillaria, and Cumarinia from Coryphantha. Mammilloydia was found nested in Mammillaria (Butterworth & al. 2002; Butterworth & Wallace 2004; Bárcenas & al. 2011; Vázquez-Sánchez & al. 2013), and all authors argue Mammilloydia should therefore no longer be recognized at generic rank. The Mammillaria assemblage therefore remains one of the Cactaceae groups that need further detailed study. Some nodes were so far only weakly supported, and final conclusions regarding the monophyly and generic limits of Mammillara must await a more extensive sampling, especially for Coryphantha and Escobaria; only then will firm taxonomic and nomenclatural conclusions be possible.

= Rooksbya (Backeb.) Backeb., Cactaceae Handb. Kakteen. Pereskioideae Opuntioideae 4: 2165. 1960. Phylogenetic studies so far resolved Neobuxbaumia as closely related to Cephalocereus and Pseudomitrocereus (Arias & al. 2003; Arias & Terrazas 2006; Hernández-Hernández & al. 2011). However, these studies did not specifically focus on Neobuxbaumia, and its generic limits are therefore not yet firmly established. Arias & al. (2003) found Neobuxbaumia in a weakly supported polytomy with Cephalocereus and Pachycereus fulviceps (F. A. C. Weber ex Schumann) D. R. Hunt (= Pseudomitrocereus) as sister to both. The two Cephalocereus species were well supported as sister to each other, but could not be separated from Neobuxbaumia in any tree (Arias & al. 2003). Bárcenas & al. (2011) and Hernández-Hernández & al. (2011) found Neobuxbaumia to be polyphyletic but the relevant nodes were weakly supported, therefore a monophyletic Neobuxbaumia is neither confirmed not contradicted by the currently available data.

Found to be polyphyletic by Vázquez-Sánchez & al. (2013), with the type species sister to the rest of the mammilloid clade, but support <50%, while N. matehualensis Backeb. was nested in Coryphantha with maximal support.

Opuntia is the second-largest genus of the family Cactaceae. As in all species-rich Cactaceae groups, numerous different generic conceps with a varying number of segregate genera have been suggested for Opuntia. Both extensive splitting (e.g. Backeberg 1966) or lumping into a broadly defined Opuntia were put forward (Rowley 1958; Benson 1982). The first phylogenetic study by Wallace & Dickie (2002) based on the rpl16 intron found Opuntia in the broad sense to be polyphyletic. For the revised generic classification they presented based on their data, they argued for splitting Opuntia, because otherwise further genera (e.g. Pereskiopsis, Pterocactus) were also nested within Opuntia and merging those would make Opuntia a highly heterogenous assemblage. Therefore, Wallace & Dickie suggested reinstating the earlier-proposed Opuntia segregates Austrocylindropuntia, Brasiliopuntia, Consolea, Corynopuntia, Cumulopuntia, Cylindropuntia, Grusonia, Maihueniopsis, Miqueliopuntia, Nopalea, Tephrocactus, and Tunilla. Opuntia s.str. was thus restricted to the taxa with flattened stems and reticulate pollen. This concept was entirely adapted by Hunt (2006), and largely by Nyffeler & Eggli (2010b). Griffith & Porter (2009), using data from plastid trnL-F and nuclear ITS, found Opuntia in this restricted sense to additionally include Consolea and Nopalea, the clade including all these genera received 100% support, and both Consolea and Nopalea were also as monophyletic with 100%. The tree resolution, however, did not allow an immediate conclusion on the delimitation of these genera. Nopalea used to be separated from Opuntia s.str. because it differs primarily in its hummingbird-syndrome flowers. Nevertheless, it was repeatedly found to be nested in Opuntia (Wallace & Gibson 2002; Griffith & Porter 2009; Barcenas & al. 2011; Hernández-Hernández & al. 2011; Majure & al. 2012) and is therefore no longer maintained as separate genus. The relationship of Consolea to Opuntia has remained more difficult to resolve, but available data suggest it is not part of Opuntia (see also notes under Consolea).

Ortegocactus Alexander in Cact. Succ. J. (Los Angeles) 33: 39. 1961 sec. Vazquez-Sánchez & al. (2013). — Type: Ortegocactus macdougallii Alexander Merging Ortegocactus into Mammillaria was proposed by Hunt & Taylor (1990) and Barthlott & Hunt (1993). The sole species, O. macdougallii, was first sampled by Butterworth & Wallace (2004) and found nested in Mammillaria, so the authors argued future transfer to Mammillaria may be justified, but must await further clarification of generic limits in this group. Vázquez-Sánchez & al. (2013) found O. macdougallii not nested in Mammillaria, but in a weakly supported polytomy in the mammilloid clade, suggesting maintaining it as a separate genus for the time being.

Phylogenetic studies based on morphological and molecular data show consistently that Pachycereus s.str. is a monophyletic group with five species (Arias & al. 2003; Arias & Terrazas 2006, 2009; Arias & al. 2012). Other species previously considered in Pachycereus (Buxbaum 1961; Gibson & Horak 1978; Anderson 2001; Hunt 2006; Nyffeler & Eggli 2010b) have been transferred to Lemaireocereus, Lophocereus, and Pseudomitrocereus. More inclusive and robust new evidence may corroborate or refute the current delimitation of these last genera. Pachycereus s.str. includes tree-like species, interareolar grooves on the stems, abundant trichomes on the flower, and flexible spines on the fruit. The genera Backebergia and Pterocereus (both monotypic) remain inconclusive on molecular data available (Arias & al. 2003; Hernández-Hernández 2011); therefore their recognition as separate genera remains premature. Recent monograph by Arias & Terrazas (2009).

The generic circumscription of Peniocereus was revised based on the molecular phylogenetic study of Arias & al. (2005). Their study based on plastid trnL-F and rpl16 found Peniocereus polyphyletic, its species resolved in three lineages. Peniocereus subg. Pseudoacanthocereus Sánchez-Mej. was found to be nested in Acanthocereus, yet both were also paraphyletic. For a classification reflecting these relationships, Peniocereus subg. Pseudoacanthocereus would need to be transferred to Acanthocereus. The other major Peniocereus clade found by Arias & al. (2005) corresponds to Peniocereus subg. Peniocereus. Peniocereus serpentinus (Lag. & Rodr.) N. P. Taylor was resolved as a separate lineage. Since it is the type species of the earlier-proposed genus Nyctocereus, Arias & al. (2005) suggested reinstating it as monotypic.

Pereskia has been repeatedly found to be paraphyletic by Nyffeler (2002), Edwards & al. (2005), and Butterworth & Edwards (2008). The genus forms a grade at the base of the Cactaceae, with a northern clade including Mesoamerican and Caribbean pereskias as the first branching group followed by a southern clade, with mainly the Andean pereskias, which also include the nomenclatural type of Pereskia (Butterworth & Wallace 2005; Edwards & al. 2005). No nomenclatural changes to reflect the paraphyly of Pereskia were proposed by Edwards & al. (2005), who preferred their results to be tested with additional genes before suggesting a new classification for Pereskia. Also, no generic name was readily available for the northern Pereskia clade — the type of the earlier-proposed segregate Rhodocactus was in the southern clade together with the type of Pereskia itself. Pereskia was accepted as polyphyletic to reflect its morphological differences to the rest of the Cactaceae. Both Pereskia clades have characters that are interpreted as ancestral within Cactaceae, such as a woody stem, the presence of true leaves, a flower morphology that differs from the rest of the Cactaceae and C3 photosynthesis. Only recently, the northern pereskias were segregated as Leuenbergeria, yet this segregation also received criticism because the two clades are hard to distinguish morphologically ( http://www.mobot.org/MOBOT/research/Edge/apr13/apr13lit.shtml; Hunt 2013). Seeking a compromise between molecular phylogenetic hypotheses and nomenclatural stability, Rowley (2013) suggested a subgenus Leuenbergera (note the different spelling!) for the northern Pereskia clade. Monograph by Leuenberger (1986).

= Rhipsalis subg. Ac anthorhipsalis K. Schum., Gesamtbeschr. Kakt.: 615. 1898 = Acanthorhipsalis (K. Schum.) Britton & Rose, Cactaceae 4: 211. 1923. The circumscription of Pfeiffera has undergone several radical changes in the past, and until the early 1980s, it was treated as a monotypic genus with P. ianthothele (Monv.) F. A. C. Weber. Kimnach (1983) subsumed Pfeiffera under Rhipsalis, while Barthlott (1987), Barthlott & Taylor (1995) and Anderson (2001, 2005) synonymized it with Lepismium. In the molecular phytogeny of Nyffeler (2002), P. ianthothele unexpectedly grouped together with two traditional Lepismium species, and widely distant from either Rhipsalis or Lepismium. Hunt (2006) broadened the concept of Pfeiffera to include nine species. This circumscription of Pfeiffera was evaluated and clarified by Korotkova & al. (2010), who rejected the circumscription of Hunt (2006), which also included the species now segregated as Lymanbensonia (see there). Recent annotated checklist by Barthlott & Taylor (1995, as Lepismium subg. Pfeiffera (Salm-Dyck) Barthlott).

Monotypic; Pseudomitrocereus fulviceps was previously included in Pachycereus or Cephalocereus, later elevated to generic rank as Mitrocereus (Backeberg 1942) and later Pseudomitrocereus (Bravo & Buxbaum, in Buxbaum 1961). Arias & al. (2003) found P. fulviceps to be unrelated to Pachycereus and instead as sister sister to a clade of Cephalocereus and Neobuxbaumia. Therefore, Pseudomitrocereus was reinstated by Arias & al. (2012). Pseudomitrocereus is characterized by having distinct fertile stem parts, flowers completely covered with trichomes, and thick axial tissue (pericarpel and receptacle; Buxbaum 1961). Its inclusion in Pachycereus was supported by non-informative attributes (e.g. growth form), shared by other members of Pachycereinae (or Echinocereinae sensu Nyffeler & Eggli 2010b). However, it is part of the clade “Cephalocereus”' according to Arias & al. (2003), composed by Cephalocerus, Neobuxbaumia, and Pseudomitrocereus. The species of this clade share the presence of prismatic crystals in the epidermis, inner stamens and nectarial chamber, while the fruit is dehiscent and the pulp is white (Arias & Terrazas 2006). Mitrocereus was based on the name Pilocereus chrysomallus Lem. as the type species, but this name represents another species included in the synonymy of Pachycereus militaris (Audot) D. R. Hunt. Consequently, Buxbaum and Bravo (Buxbaum 1961) proposed the name Pseudomitrocereus, with P. fulviceps as the nomenclatural type.

The sole species of this recently segregated genus, Punotia lagopus, was formerly placed in Austrocylindropuntia, but was recovered as sister to the remaining species of Austrocylindropuntia and Cumulopuntia by Ritz & al. (2012). It differs from Austrocylindropuntia in several characters, especially its growth form as flat, extensive cushions.

= Lodia Mosco & Zanovello in Bradleya 18: 44. 2000. Traditionally included in Turbinicarpus (see there); separated from it by Vázquez-Sánchez & al. (2013) after Turbinicarpus was found to be polyphyletic by them and previously also by Barcenas & al. (2011). Recent monograph by Lüthy (2003).

The circumscription of Rebutia s.l. vs a suite of proposed segregates (including Aylostera, Digitorebutia, Mediolobivia, Sulcorebutia and Weingartia) has been the subject of continued debate in the past 30 years. The wide circumscription (including these taxa) was adopted by Anderson & al. (2001) and Hunt (2006), but not by Anderson (2005), who recognized Sulcorebutia and Weingartia. The broad concept goes back to the consensus Cactaceae classification as summarized by Hunt & Taylor (1986), and some participants of the discussions at that time even argued that Rebulia sensu latissimo should be placed in the synonymy of an even more expanded Echinopsis. Recent molecular phylogenetic studies showed, however, that Rebutia does not belong in the Echinopsis clade (Ritz & al. 2007; Mosti & al. 2011; Schlumpberger & Renner 2012), and that the genus in this broad concept is an untenable polyphyletic assemblage, as first noted by Lendel & al. (2006). In the molecular phylogeny of Ritz & al. (2007), three independent clades with taxa of Rebutia s.l. are found, namely “Rebutia I” (including the segregates Aylostera, Digitorebutia and Mediolobivia), “Rebutia II” (conforming to Rebutia s.str.) and Weingartia (incl. Cintia and Sulcorebutia). While Rebutia s.str. is placed as sister to Browningia, Aylostera is placed in a clade with Cereus and Stetsonia (Ritz & al. 2007;
). Therefore it appears reasonable to abandon the concept of Rebutia s.l., to restrict Rebutia to the “true” rebutias, and to accept both Aylostera as well as Weingartia as separate genera. Most of the necessary new combinations have been published for Aylostera (Monti & al. 2011) and Weingartia (Hentzschel & Augustin 2008).

As explained under Hatiora, the inclusion of Rhipsalidopsis in Hatiora is not supported by recent molecular phylogenies. Calvente & al. (2011) found the two traditional Rhipsalidopsis species (R. gaertneri (Regel) Moran, R. rosea) are sister to Schlumbergera, but with moderate support. Korotkova & al. (2011), however, found Hatiora s.str., Rhipsalidopsis and Schlumbergera to form a grade, and even though support for this topology is also moderate, support for the monophyly of the three genera is maximal: therefore, Rhipsalidopsis (Easter cacti) is best kept separate from Schlumbergera (Christmas cacti). Recent annotated checklist by Barthlott & Taylor (1995, as Hatiora subg. Rhipsalidopsis (Britton & Rose) Barthlott).

The circumscription of Rhipsalis — one of the oldest genera of the family — has changed repeatedly over time, and often Hatiora, Lepismium and Pseudorhipsalis, all now accepted at generic rank, were variously subsumed under Rhipsalis. The morphology-based circumscription of Rhipsalis by Barthlott & Taylor (1995) has been entirely confirmed as monophyletic with maximal support in the molecular phylogenetic study of Korotkova & al. (2011); the same result was shown by Calvente & al. (2011b), though with a less comprehensive sampling. Rhipsalis is notable since R. baccifera (Sol.) Steam is the only species of the family that naturally occurs outside the New World. Recent annotated checklist by Barthlott & Taylor (1995).

This monotypic genus has been found in a polytomy with Brasiliopuntia + Tacinga and Opuntia s.str. (i.e. the platyopuntioids) by Griffith & Porter (2009). The study of Majure & al. (2012) confirmed that Salmiopuntia is not part of Opuntia s.str.

Schlumbergera (Christmas cacti) is one of the best-known and one of the morphologically best-defined Cactaceae genera, recognizable by its flattened stems and bright pink zygomorphic flowers. Its monophyly was confirmed by the molecular phylogenetic analysis of Calvente & al. (2010) and Korotkova & al. (2011). Recent annotated checklist by Barthlott & Taylor (1995).

Confirmed as monophyletic by Butterworth & al. (2002) and Vázquez-Sánchez & al. (2013). The generic status and limits of Echinomastus need further evaluation because it was found to be polyphyletic by Vázquez-Sánchez & al. (2013). Revisions/monographs by Heil & Porter (1994) and Hochstätter (2005).

Turbinicarpus has been found to be polyphyletic in the molecular studies of Bárcenas & al. (2011) and Hernández-Hernández & al. (2011). The most comprehensively sampled dataset of Vázquez-Sánchez & al. (2013) showed Turbinicarpus to fall into three separate clades. Turbinicarpus was re-circumscribed restricted to 11 species, while species with a tuberous root connected to the body with a long, thin neck are now segregated as Rapicactus based on these results. Two further species (T. horripilus (Lem.) V. John & Říha and T. pseudomacrochele (Backeb.) Buxb. & Backeb.) are outside the main Turbinicarpus clade (incl. Gymnocactus) and a new generic name would be needed for them. Recent treatments by Lũthy (2002) and Lüthy & Moser (2002).

Included in Espostoa s.l. by modem lexicographic treatments such as Anderson (2001, 2005) and Hunt (2006), the genus was found to be distant from the Espostoa in the Cleistocactus s.str. clade by Schlumpberger & Renner (2012). Consequently, the monotypic Vatricanici was suggested to be reinstated.

Weingartia and Sulcorebutia used to be merged in Rebutia, e.g. by Barthlott & Hunt (1993), Anderson (2001), and Hunt (2006), but were recognized by Anderson (2005). The Rebutia s.l. assemblage was found highly polyphyletic by Ritz & al. (2007), and was shown to be separated into three well-supported clades. One of these clades comprises species of Cintia, Sulcorebutia and Weingartia and includes the nomenclatural type of Weingartia. Ritz & al. (2007) suggested that all three could be merged into a single genus, for which Weingartia is the oldest name.

A family of chiefly opposite-leaved herbs comprising about 100 genera and 3000 species. The family is widely distributed in north-temperate, montane and alpine areas with a centre of diversity in the eastern Mediterranean and Irano-Turanean regions, while presence in the tropics and the southern hemisphere is limited and mostly at higher elevations (Bittrich 1993c; Rabeler & Hartman 2005a). Several taxa (especially species of Dianthus, Gypsophila and Silene) are important in the horticultural trade, while others (e.g. Stellaria media (L.) Vill.) have become widely known weedy taxa. The number of genera included here is over 10% higher than most recent estimates (Bittrich 1993c; Rabeler & Hartman 2005a; Harbaugh & al. 2010), reflecting the results of recent molecular studies on large genera (especially Minuartia, Dillenberger & Kadereit 2014) as well as retention of several genera (e.g. Myosoton, Velezia and Xerotia) that may eventually disappear. The family is monophyletic as circumscribed by Bittrich (1993c), although the “traditional” division into three subfamilies (Bittrich 1993c; Pax & Hoffmann 1934) based on stipule, petal, sepal and fruit features does not provide monophyletic groups and should be replaced with the tribe-based scheme presented by Harbaugh & al. (2010) and confirmed by subsequent studies (e.g. Greenberg & Donoghue 2011).

Consists of about 60 cushion-forming subshrubby species of the subalpine steppe region in central to southwestern Asia (Bittrich 1993b; Ghaffari 2004). Pirani & al. (2014) showed that the genus is paraphyletic in this circumscription with Allochrusa, Diaphanoptera p.p., Ochotonophila and Scleranthopsis nested within it.

monotypic genus; southwestern United States and Mexico. Hartman (2005a) noted that seed and flower characters suggest a close relationship to Scopulophila. Greenberg & Donoghue (2011) showed a similar result from molecular data.

About 160 species, in north-temperate areas, the Mediterranean, and Andean South America. Harbaugh & al. (2010), Greenberg & Donoghue (2011) and most recently Sadeghian & al. (2015) have sampled Arenaria and, between their results, have removed about one-half of the species into four segregate genera not aligning in the same tribe as Arenaria. Sadeghian & al. (2015) found that four of the five remaining subgenera that McNeill (1962) recognized form Arenaria s.str., with the placement of A. subg. Dicranilla (Fenzl) F. N. Williams still unknown. While a few of the infrageneric groups recognized by McNeill (1962) are confirmed by molecular results (e.g. A. subg. Leiosperma McNeill, A. sect. Plinthine (Rchb.) McNeill), most are not.

Recently revised by Frajman & al. (2013), who recognized six, mostly European species. Well supported as monophyletic by several unlinked DNA sequence regions, and also as sister to Viscaria (Frajman & al. 2009b; see under Viscaria).

About 20 species in the Mediterranean region. Greenberg & Donoghue (2011) showed Bufonia as sister to the remainder of Sagineae (except for Drypis), while Dillenberger & Kadereit (2014) found it was an unsupported sister to a clade containing Minuartia s.str. and Mcneillia.

Six species found from western North America south to Chile. Sosa & al. (2006) found Cardionema and Scopulophila clustered with Cerdia. Greenberg & Donoghue (2011) showed Cardionema belonging to a poorly resolved group of genera in the tribe Polycarpaeae.

Includes 100 or, more likely, close to 200 north-temperate species, especially diverse in the eastern Mediterranean. The genus is in need of monographic study. The most recent infrageneric classification is presented by Schischkin (1936); even with corrected nomenclature and inclusion of extra-Russian taxa, it is not likely to be representative of relationships in the genus. Greenberg & Donoghue (2011) included 39 species of Cerastium in their study and found several interesting points. Cerastium subg. Dichodon (Bartl. ex Rchb.) Boiss. should be treated as a genus, Dichodon (see there), being a sister to Holosteum. As in Dianthus, resolution of the species was very poor, most species falling into either a polytomy of 11 species or one of 23. They also found Cerastium formed a clade within Stellaria. These genera are considered quite distinct by nearly all workers, so this must be investigated further.

Monotypic; endemic to Mexico. Placement within the Polycarpeae is probable (near Cardionema and Scopulophila?), but Sosa & al. (2006) suggested that further study is needed. In a broader survey using a different voucher, Greenberg & Donoghue (2011) found Cerdia clustering near Drymaria.

Originally including only C. sedoides found in mountains of Europe, but Dillenberger & Kadereit (2014) proposed expanding it to 19 species of Eurasia and western North America; Mosyakin suggests 23 to account for some additional eastern European taxa not yet transferred to Cherleria (S. Mosyakin, unpubl. data). Formerly included (with Pseudocherleria) in Minuartia sect. Spectabiles (Fenzl) Hayek, Dillenberger & Kadereit (2014) found the two groups segregated into different clades far from Minuartia s.str., proposing the recognition of both Cherleria and Pseudocherleria.

With about 300 species, Dianthus is the second largest genus in the Caryophyllaceae. Dianthus is most diverse in southeastern Europe and southwestern Asia. No recent monographic work has been undertaken; the most comprehensive infrageneric classification is presented in Pax & Hoffmann (1934). Although Greenberg & Donoghue (2011) included 37 species in their analysis, virtually no resolution was found; 26 species formed a polytomy. May include Velezia (see there).

Five species of the Arctic, central Europe, and Iran. Treated as Cerastium subg. Dichodon (Bartl, ex Rchb.) Boiss. in most recent works. Greenberg & Donoghue (2011) found that the two sampled species of Dichodon formed a clade sister to Holosteum, and together formed a clade sister to Cerastium + Moenchia.

A genus of four or five Himalayan species. Most recently treated as a subgenus of Arenaria (McNeill 1962). Sadeghian & al. (2015) suggested the genus be again recognized after finding that the one sampled species clustered near Eremogone, either as a sister to Silene or between Eremogone and Silene. They also noted that the result reported by Greenberg & Donoghue (2011), showing Arenaria przewedskii Maxim, clustering with members of Lepyrodiclis and Pseudostellaria, suggests that Dolophragma may be polyphyletic.

About 50 species, all but two found only in the New World. Little is known about relationships within Drymaria. Duke's (1962) preliminary revision, in which he described but did not validly publish 17 series, is the only recent comprehensive study. Greenberg & Donoghue (2011) included all four sampled taxa and show a poorly resolved, possibly polyphyletic genus.

monotypic; eastern Mediterranean. Formerly placed in an isolated position within the Caryophylloideae. Molecular studies, including Harbaugh & al. (2010), Greenberg & Donoghue (2011) and Dillenberger & Kadereit (2014), place Drypis as sister to all other sampled taxa in tribe Sagineae.

About 90 species, most diverse in eastern Asia and western North America. Harbaugh & al. (2010) confirmed the wide separation from Arenaria that Fior & al. (2006) reported. Broad sampling is still needed to resolve infrageneric relationships; existing information (Sadeghian & al. 2015) is not consistent with the extant classification (McNeill 1962) erected for these taxa in two subgenera under Arenaria.

Gypsophila includes about 150 species and is especially diverse in the eastern Mediterranean and southwestern Asia. Most of the infrageneric classification is derived from Barkoudah's (1962) monograph of Gypsophila and three related genera. Greenberg & Donoghue (2011) included 24 species in their analysis and found Gypsophila to be polyphyletic, with most species forming a clade sister to Saponaria and four species resolving close to Dianthus/Petrorhagia; one of these species, G. muralis L., is here treated as Psammophiliella. Pirani & al. (2014) found G. cerastioides D. Don nested within Acanthophyllum. Recognition of Bolbosaponaria seems likely; while Greenberg & Donoghue (2011) found B. bucharica (B. Fedtsch.) Bondarenko clustered with two other species of Gypsophila, Pirani & al. (2014) found it to be a sister taxon to Diaphanoptera afghanica Podl.

A chiefly central and southeastern European group with four to 16 species depending on species delimitations (Frajman & Oxelman 2007). Heliosperma has been conserved over its senior synonym Ixoca (Barrie 2011), as proposed by Frajman & Rabeler (2006). Frajman & al. (2009a) analysed several independent nuclear and plastid loci showing strong support for monophyly of the genus, although it appears to have a complex history, possibly involving ancient hybridization events.

Three to four species of temperate Eurasia. While Harbaugh & al. (2010) found that Holosteum and Moenchia were sister taxa, Greenberg & Donoghue (2011) found Holosteum and Dichodon to be sisters, with that clade a sister to the clade that include Cerastium and Moenchia.

monotypic; native to the Canary Islands and the Mediterranean. Greenberg & Donoghue (2011) showed Illecebrum belonging to a poorly resolved group of genera in the Polycarpaeae, closest to Cardionema as shown by Kool & al. (2007).

Three species of central Asia. Sadeghian & al. (2015) found two species formed a clade sister to one including Odontostemma and Pseudostellaria. Greenberg & Donoghue (2011) noted that L. holosteoides clustered with Stellaria monosperma Buch.-Ham. ex D. Don.

Seven species of the Mediterranean, southwestern Asia, and western North America. Fior & al. (2006) and Harbaugh & al. (2010) both showed Loeflingia and Polycarpon clustering together; a result not shown in the Kool & al. (2007) study of Polycarpon. Greenberg & Donoghue (2011) found it clustered in a poorly resolved clade including eleven other genera of Polycarpaeae.

This circumscription, including around twenty species, is strongly supported as monophyletic (e.g. Popp & al. 2008; Greenberg & Donoghue 2011), with the African Uebelinia nested within. However, its relationships to Silene are not fully resolved (see under Silene).

About 54 species, chiefly in Mediterranean Europe and eastward into south-central Asia. While several molecular studies had shown Minuartia to be polyphyletic, Dillenberger & Kadereit's (2014) study is the most comprehensive to date, including the first sequences for Minuartia sect. Minuartia. They found that the 96 species of Minuartia sampled belonged to ten different clades representing four different tribes. This circumscription restricts Minuartia to two of the twelve sections of Minuartia subg. Minuartia recognized by McNeill (1962).

Four species of the mountains of Turkey and Iran. Treated as Minuartia [sect. Lanceolatae (Fenzl) Graebn.] ser. Dianthifoliae Mattf. by McNeill (1962), Dillenberger & Kadereit (2014) found the sampled taxa forming an isolated clade that could be interpreted as sister to a clade that included Colbanthus, Facchinia, Sabulina and Sagina.

Three species found in western and central Europe. While Harbaugh & al. (2010) noted that Moenchia and Holosteum were sister taxa, Greenberg & Donoghue (2011) found that Moenchia was a sister to Cerastium.

Nine species of eastern North America. Dillenberger & Kadereit (2014) found Geocarpon was nested within a clade consisting of Minuartia sect. Uninerviae (Fenzl) Mattf.; that clade was sister to a clade containing Triplateia and three species of Stellaria on the basis of matK sequences.

Monotypic; temperate Eurasia. Treatment of the species as Stellaria aquatica L. may be warranted pending a serious review of Stellaria. It was found clustering near species of Stellaria sect. Stellaria by both Harbaugh & al. (2010) and by Greenberg & Donoghue (2011) in a study that more densely sampled Stellaria.

About 65 species of the Himalayas and adjacent southern China. Considered as a subgenus of Arenaria by many (e.g. McNeill 1962), Harbaugh & al. (2010) proposed, and Sadeghian & al. (2015) confirmed, that Odontostemma should be treated as a genus, clustering with Cerastium and Stellaria rather than Arenaria. Work on new combinations necessary for recognizing most species in Odontostemma is underway (R. Rabeler & W. Wagner, unpubl. data).

In a study mainly addressing Gymnocarpos, Oxelman & al. (2002) found Paronychia to be polyphyletic, with the subgenera Paronychia and Siphonychia forming a strongly supported sister group to Gymnocarpos, whereas species in P. subg. Anoplonychia (Fenzl) Rchb. were found to be more closely related to Herniaria and Philippiella. This was confirmed by Greenberg & Donoghue (2011). The genus consists of 110 (Hartman & al. 2005) or more than 150 species (Bittrich 1993b). It is one of the large genera in the family that has not yet been extensively studied with DNA sequence data, especially in P. subg. Anoplonychia (Fenzl) Rchb. (only two of 48 species sampled).

Comprising 33 species, ranging from the Canary Islands east to Kashmir. Shown to cluster as sister to a clade including Dianthus and Velezia by Harbaugh & al. (2010), Greenberg & Donoghue (2011) and Pirani & al. (2014). The genus has not been widely sampled. Although kept separate by Bittrich (1993c), most recent treatments of the genus include Kohlrauschia as a section in Petrorhagia following the monograph of Ball & Heywood (1964). This may deserve further investigation since Greenberg & Donoghue (2011) cited three samples in their study; a voucher of “P. velutina Guss.” (a later name for P. dubia (Raf.) G. López & Romo) was shown as a sister to a clade including P. saxifraga (L.) Link and a second voucher of P. dubia; the identification of the vouchers should be verified.

monotypic; eastern and southern Africa. Kool & al. (2012) placed P. campestris as sister to the monotypic Sphaerocoma; both genera form a clade that is sister to a clade containing Polycarpaea and Polycarpon.

A paleotropical group of 50+ species. Kool & al. (2007, 2012) found it to be polyphyletic; additional sampling is required to treat the genus, resolve infrageneric relationships and decide how some small genera (e.g. Haya, Xerotia) should be treated.

Monotypic; Mediterranean and western North America. Kool & al. (2007) found Polycarpon was polyphyletic with species distributed in three clades. Two of these included species of Polycarpaea and were removed from Polycarpon. The third included members of the P. tetraphyllum group; tight relations in the remaining clade suggested reduction to one polymorphic species.

Four species of central Asia. Most often treated as Gypsophila subg. Macrorrhizaea, but both Greenberg & Donoghue (2011) and Pirani & al. (2014) showed P. muralis as sister to a clade of Dianthus/ Petrorhagia, clearly separate from the remainder of Gypsophila.

Comprises 12 species found in the Caucasus region, arctic Asia and northwestern North America. Formerly included (with Cherleria) in Minuartia sect. Spectabiles (Fenzl) Hayek, Dillenberger & Kadereit (2014) found the two groups segregated into different clades far from Minuartia s.str., proposing the recognition of both genera.

A group of about 20 species, mostly in central Asia east to Japan, with one species in Europe and three in western North America. The few species thus far sampled cluster near Lepyrodiclis and Odontostemma. Greenberg & Donoghue (2011) included four species and found the American P. jamesiana (Torr.) W. A. Weber & R. L. Hartm. did not cluster with the three Asian species; their report showing Stellaria jamesiana Torr. (= P. jamesiana (Torr.) W. A. Weber & R. L. Hartm.) clustering among Cerastium is based on a misidentified specimen of C. arvense L.

A genus of 17 Andean species that clusters close to Drymaria, a result first reported by Smissen & al. (2003) and confirmed in four further studies. This contradicts the earlier placement (e.g. Bittrich 1993c) as a member of subfamily Alsinoideae.

Comprising c. 65 species (possibly 70, including some eastern European and western Asian taxa not yet transferred to Sabulina: S. Mosyakin, unpubl. data), all but two found in the northern hemisphere (Europe, Asia and North America). Including members of six sections of McNeill's (1962) Minuartia subg. Minuartia as well as Stellaria fontinalis (Short & Peter) B. L. Rob., these species form a clade that is sister to a clade including Colobanthus, Facchinia and Sagina. Rabeler & al. (2014) suggested this clade may be further subdivided, possibly recognizing four other genera.

A genus of about 30 species, most diverse in northtemperate and arctic areas with a few taxa found on some tropical mountains. Sampling shows Sagina to be monophyletic, although infrageneric relationships have not been studied.

About 40 species, most diverse in the Mediterranean and southwestern Asia. The most comprehensive monograph dates from 1910 (Simmler 1910), with Shults (1989) providing an updated account for Russian taxa. Up to now, sampling has been minimal and offers no information on how related genera (Bolbosaponaria, Cyathophylla, Pleioneura, etc.) may best be treated.

About 12 species native to Eurasia and Australasia. Smissen & al. (2003) found Scleranthus to be monophyletic and to be treated as two subgenera: S. subg. Scleranthus (three species, Eurasia) and S. subg. Mniarum (J. R. Forst. & G. Forst.) Pax) (nine species, southeastern Australasia). Dillenberger & Kadereit (2014) found Scleranthus was sister to one of ten clades of Minuartia s.l., treated by them as Cherleria.

Monotypic; in deserts from Somalia east to Pakistan. Kool & al. (2012) noted that Sphaerocoma is sister to the monotypic Pollichia and together they form a sister clade to one including Polycarpaea and Polycarpon.

A genus of about 150 to more likely 200 species of Eurasia and North America, most diverse in the mountains of central Asia. Stellaria is in need of a monographic revision; the most recent infrageneric classification is that of Pax & Hoffman (1934). Greenberg & Donoghue (2011) conducted the most extensive sampling of Stellaria to date, including 44 species. Stellaria is clearly polyphyletic and in need of further study: S. obtusa Engelm. appeared as a sister to a clade including Honckenya, Schiedea and Wilhemsia; three Mexican/Caribbean species were sister to Minuartia sect. Uninerviae (Fenzl) Mattf. (= Mononeuria of Dillenberger & Kadereit 2014); S. americana (Porter ex B. L. Rob.) Standl. clustered with Pseudostellariajamesiana (Torr.) W. A. Weber & R. L. Hartm.; and S. holostea, the type of Stellaria, appeared as sister to the clade that includes Cerastium, Dichodon,Holosteum, Moenchia and the majority of Stellaria species sampled.

Stipulicida Michx., Fl. Bor.-Amer. 1: 26, pl. 6. 1803 sec. Bittrich (1993c). — Type: Stipulicida setacea Michx. Stipulicida is found only in the southeastern United States and Cuba. Long thought to be monotypic, a recent morphological study (Poindexter & al. 2014) proposed recognition of two species. Work is underway to confirm placement in the Polycarpaeae (K. Neubig & R. Rabeler, unpubl. data).

Monotypic; endemic to central Mexico. Treated by McNeill (1962) as Minuartia subg. Hymenella (Ser.) McNeill. Harbaugh & al. (2010) and Greenberg & Donoghue (2011) both reported it as sister to Geocarponminimum Mack., a species endemic to the Ozark region of the United States. Dillenberger & Kadereit (2014) found that it was a sister taxon to three species of Stellaria from Mexico and the Caribbean. This clade was, depending on the gene chosen, either sister to Mononeuria (Minuartia sect. Uninerviae+ Geocarpon) (matK) or sister to a clade including Honckenya, Schiedea and Wilhelmsia (ITS).

One or four species, native to Eurasia. While usually thought to be closely related to Saponaria, both Harbaugh & al. (2010) and Greenberg & Donoghue (2011) found a potential relation with Gypsophila based on different vouchers: sister to Gypsophila in the former study, clustering near the base of a Gypsophila clade in the latter.

Six species occurring from the Mediterranean east to Afghanistan. May be included in Dianthus; Harbaugh & al. (2010) and Greenberg & Donoghue (2011) both found V. rigida nested in Dianthus, while Pirani & al. (2014) showed Velezia as a sister to Dianthus.

Monotypic; arctic northwestern North America and eastern Asia. Harbaugh & al. (2010) found Wilhelmsia and Honckenya are sister to each other and both are the closest relatives to the Hawaiian Schiedea.

Monotypic; Arabia. Found to be nested in one of the clades of Polycarpaea by Kool & al. (2012); placement awaits further resolution of polyphyly in Polycarpaea.

Chenopodiaceae Vent. sec. Müller & Borsch (2005).

The family Chenopodiaceae is cosmopolitan predominantly occurring in temperate and subtropical regions, and especially in semi-arid or arid environments (Kühn 1993; Kadereit & al. 2003). Our delimitation of the Chenopodiaceae follows the concept of Ulbrich (1934), and Kühn (1993) with the exception of the Polycnemoideae (see Amaranthaceae). Considering that the core of Chenopodiaceae (composed of Betoideae, Camphorosmoideae,Chenopodioideae, Salicornioideae, Salsoloideae and Suaedoideae) is likely to be monophyletic, we maintain the Chenopodiaceae as a family distinct from the Amaranthaceae in line with a series of current taxonomic treatments and morphological, physiological and phylogenetic studies (Tzvelev & al. 1996; Welsh & al. 2003; Zhu & al. 2003; Kadereit & al. 2005; Kapralov & al. 2006; Voznesenskaya & al. 2007; Akhani & al. 2007; Zacharias & Baldwin 2010; Kadereit & al. 2010; Sukhorukov 2010; Flores-Olvera & al. 2011; Sukhorukov & Kushunina 2014). We believe that name stability is important as it facilitates the assignment of genera to the respective major Amaranthaceae and Chenopodiaceae clades in line with the vast literature on Chenopodiaceae. The monophyletic core Chenopodiaceae had already been found with maximum support based on matK-trnK sequence data (Müller & Borsch 2005a), although relationships of the six major subfamilies were not clear. Much progress has been made in the last decade on the internal relationships of Chenopodiaceae. Schütze & al. (2003) found two major clades of Suaedoideae Ulbr., to which Bienertia is sister. The Salicornioideae were clearly identified as monophyletic and are a lineage of about 90 species growing worldwide in coastal and inland saline habitats (Kadereit & al. 2006) with often succulent-articulated stems. Phylogenetic analysis yielded good support for the Camphorosmoideae that include several major lineages of mostly steppe, semi-desert and desert plants (Kadereit & Freitag 2011), but genera of the Salsoloideae such as Salsola L. were depicted as largely polyphyletic (Akhani & al. 2007; Kadereit & Freitag 2011). The Chenopodioideae were confirmed as monophyletic, although the members of the genus Chenopodium in its pre-phylogenetic circumscription appeared scattered across the subfamily, leading to a re-circumscription at genus and tribal level (Fuentes-Bazán & al. 2012a, b).

This monotypic genus is distributed in coastal habitats of California and according to Hohmann & al. (2006) it belongs to Betoideae-Hablitzieae. Together with its sister genus Oreobliton, which is distributed in northern Africa, Aphanisma represents an interesting example of a western Eurasian-western North American disjunction (Kadereit & Baldwin 2012).

This monotypic genus is only known from northern Sichuan province, China, near Nanping (Chu 1987). Archiatriplex is interpreted as an ancient lineage of the Chenopodieae (formerly Atripliceae), based on molecular phylogenetic and morphological evidence (Kadereit & al. 2010).

Arthrocnemum belongs to Salicornioideae. In its current circumscription, the genus consists of two disjunctly distributed species, the Eurasian and northern African A.macrostachyum (Moric.) K. Koch and the North American and Mesoamerican A.subterminale (Parish) Standl. Both are stem-succulent hygrohalopyhtes (Kadereit & al. 2006a).

Atriplex is the most species-rich genus within Chenopodiaceae with c. 300 species. This cosmopolitan genus comprises annual or perennial herbs, subshrubs and shrubs that are often prominent floristic elements of steppes, semi-deserts and coastal habitats (Kadereit & al. 2010). Most species of Atriplex are C4 plants that all belong to one large C4 lineage. Many species of the genus are halophytes and possess salt glands. Ontogenetic studies showed that the two more or less concrescent “bracteoles” that envelop the fruit and that are characteristic of Atriplex are better interpreted as two tepals (Flores-Olvera & al. 2011). The circumscription of Atriplex has changed over time, and several infrageneric classifications have been proposed (Flores & Davis 2001; Kadereit & al. 2010). Recent phylogenetic studies based on molecular data (Kadereit & al. 2010; Zacharias & Baldwin 2010) show that Atriplex in its traditional circumscription is not monophyletic and includes several satellite genera that have been separated in the past. A new infrageneric classification is needed. Previously Atriplex was placed in the tribe Atripliceae. However, because the previous Chenopodieae are paraphyletic to Atripliceae the tribes were merged together by Fuentes-Bazán & al. (2012b). The accepted name of the tribe in the new, monophyletic definition is Atripliceae.

Axyris, together with Ceratocarpus and Krascheninnikovia, constitutes the Axyrideae (Kadereit & al. 2010). The genus consists of six species mainly concentrated in the mountains of central Asia and eastern Siberia (Sukhorukov 2011); some species (especially A. amaranthoides L.) occur as alien weeds in Eurasia and North America beyond their native range. Investigated species of the genus show heterocarpy (Sukhorukov 2005, 2011).

Beta comprises seven species of annuals or biennial and perennial herbs with a storage root. Beta is subdivided into two sections and is the only genus of tribe Beteae. Beta sect. Procumbentes Ulbr. (≡ B. [unranked] Patellares Tranzschel) was excluded from Beta on the basis of molecular phylogenetic and morphological results (see under Patellifolia; Hohmann & al. 2006; Kadereit & al. 2006b). Beta vulgaris and its various cultivated varieties (sugar beet, beetroot, fodder beet and chard) are the economically most important crops within Caryophyllales (McGrath & al. 2011). For B. vulgaris the chloroplast genome (Li & al. 2014) and the nuclear genome (Dohm & al. 2013) have been sequenced recently.

The genus comprises three species that grow in temporarily wet saline habitats in Iran and surrounding countries (Akhani & al. 2005, 2012). The discovery of Akhani & al. (1997) and Freitag & Stichler (2002) that B. cycloptera Bunge is a C4 plant without Kranz tissues triggered a large number of physiological, biochemical and genetic studies investigating C4 photosynthesis in this genus (Akhani & al. 2009).

The genus Caroxylon was resurrected by Tzvelev (1993) and then confirmed and re-circumscribed based on molecular and morphological evidence (Akhani & al. 2007). In that circumscription, it is the most diverse genus in Salsoloideae with c. 100 species distributed in central and southwestern Asia, the Mediterranean region and northern and southern Africa (Feodorova 2011). Feodorova & Samigullin (2014) revealed four clades within Caroxylon s.l. and provisionally advocated further splitting of the genus, with recognition of Caroxylon s.str., a recircumscribed Nitrosalsola, and possibly two other segregate genera, based on molecular and morphological evidence.

Chenopodiastrum is a widespread new genus with six or seven species and segregated from Chenopodium s.l. Its recognition is based mainly on molecular phylogenetic studies (Fuentes-Bazán & al. 2012a, b). The genus is subdivided into two groups, for which sectional rank was proposed (Mosyakin 2013).

Chenopodium has been considered one of the most diverse genera within Chenopodiaceae with c. 150 species (Kühn 1993), or even up to 250 species (under a narrow species concept). The circumscription has considerably changed over time, and several infrageneric classifications have been proposed. In a wide sense, Kühn (1993) and Mosyakin & Clemants (1996) recognized three subgenera: C. subg. Ambrosia A. J. Scott, C. subg. Blitum (L.) Hiitonen and C. subg. Chenopodium, and this classification was followed by several authors in recent treatments for the genera. However, it was proposed, based initially on morphological data, to include C. subg. Ambrosia into the re-circumscribed genus Dysphania R. Br. (Mosyakin & Clemants 2003, 2008; Clemants & Mosyakin 2003; Zhu & al. 2003). Recent phylogenetic studies based on molecular data (Fuentes-Bazán & al. 2012a, b) have shown that Chenopodium in its traditional circumscription is not monophyletic and consists of six independent lineages. Fuentes-Bazán & al. (2012b) also gave the morphological descriptions of the segregates, including Chenopodium s.str., which still remains the most species-rich and most widespread genus of the group. Chenopodium belongs to Atripliceae (earlier Chenopodieae), which is monophyletic in the circumscription by Fuentes-Bazán & al. (2012b). The typification of the genus Chenopodium is debated. If the same solution is adopted for Chenopodium as that proposed for Salsola by Akhani & al. (2014), i.e. the recognition of the lectotype proposed under the “American Code” (Arthur & al. 1907) (C.rubrum L. in our case), then the genus recognized here as Oxybasis should be called Chenopodium s.str., and the genus containing C. album L. (the lectotype of Chenopodium as recognized here) should probably be called Rhagodia, which will have disastrous consequences for taxonomy and nomenclature of the group (see discussion in Mosyakin & Clemants 1996; Fuentes-Bazán & al. 2012b).

= Gyroptera Botsch. in Bot. Zhurn. (Moscow & Leningrad) 52: 807. 1967. This genus has not yet been included in any molecular phylogenetic study. It belongs to the African Arabian subtribe Sevadinae, presumably included in Salsoleaae (Botschantzev 1975).

Climacoptera s.str. represents a monophyletic C4 genus within Caroxyleae. The genus is distributed in central and southwestern Asia and comprises only annual species. Highly contradictory species numbers, ranging from six to c. 42, are given (Akhani & al. 2007; Pratov 1986).

Corispermum comprises 60–65 annual psammophytic (rarely glareophytic) species naturally distributed mainly in Eurasia, with fewer than ten species native in North America (Mosyakin 1995). Species delimitations and distribution are poorly understood because of high morphological variability and possible recent explosive radiation of local races. There is one molecular phylogenetic study of Corispermum by Xue & Zhang (2011) that is limited to Chinese species and shows a rather poor infrageneric resolution. The genus is in need of a taxonomic revision based on comprehensive molecular phylogenetic and morphological studies.

Four species are currently recognized in Dissocarpus (Australian Camphorosmeae). The genus is endemic to Australia (Wilson 1984). It is closely related to Didymanthus and Eriochiton (Cabrera & al. 2009).

A rare endangered monotypic genus of Camphorosmeae growing on coastal cliffs in the central Mediterranean (Iamonico & Kadereit 2013). Eokochia is sister to the North American genus Neokochia (Kadereit & Freitag 2011), thus belonging to a clade showing an ancient Mediterranean-North American disjunction.

The two species of Extriplex are endemic to the California Floristic Province. Extriplex belongs to the Archiatriplex clade within Chenopodieae, formerly Atripliceae (Kadereit & al. 2010; see Zacharias & Baldwin 2010 for detailed information on the genus).

The monotypic genus belongs to the Hablitzieae-Betoideae (Hohmann & al. 2006; Kadereit & al. 2006). Hablitzia tamnoides is one of the very few climbing species in Chenopodiaceae. Annual shoots grow from a fleshy root in this species, which is endemic to Caucasus and NW Iran.

Halimione consists of three species (one annual, two perennial), which are distributed in Europe, the Mediterranean and western Asia. The genus is often included in Atriplex. Molecular and morphological data, however, support the generic status of Halimione (Kadereit & al. 2010), which is sister to the species-rich Atriplex in the tribe Chenopodieae, formerly Atripliceae.

Halimocnemis is an aggregate of Irano-Turanian annual species that is phylogenetically not well resolved. Based on phylogenetic studies (Akhani & al. 2007), a broad concept was adopted in which Gamanthus,Halanthium and Halotis are included. Further phylogenetic studies are required for possible inclusion of genera such as Halarchon, Physandra and Piptoptera.

Halocnemum belongs to Salicornioideae and comprises two hygrohalophytic species of shrubs. The genus is distributed in the southern Mediterranean and southern, western and west-central Asia and is closely related to Halopeplis and Halostachys (Kadereit & al. 2006).

= Agathophora (Fenzl) Bunge in Mém. Acad. Imp. Sci. Saint-Pétersbourg, Sér. 7, 4(11): 19, 92. 1862. Halogeton belongs to Salsoleae s.str. and is likely monophyletic (Akhani & al. 2007). This Eurasian genus, one species of which is also found in the southwestern and partly central United States as a widespread invasive alien, comprises c. five annual and perennial species and is often found in saline habitats.

Halopeplis comprises three species of annual and perennial hygrohalophytes distributed in the southern Mediterranean, South Africa and southern, western and central Asia. The genus belongs to Salicornieae and is closely related to Halocnemum and Halostachys (Kadereit & al. 2006).

This monotypic genus of Salicornieae is distributed in central, southern and western Asia and southern and eastern Europe. It is closely related to Halocnemum and Halopeplis (Kadereit & al. 2006). Nomenclatural note: Pfeiffer (1874) had chosen Halostachys songarica Schrenk as the type of Halostachys, but this species was by that time already placed in the new genus Halopeplis (see Piirainen 2015 for details). A proposal has been published to conserve the name Halostachys with H. caspica as its conserved type (Piirainen 2015).

Halothamnus belongs to Salsoleae s.str. and is likely monophyletic (Akhani & al. 2007). The genus comprises 21 species, most of which are small shrubs or subshrubs, only two species are annuals. It is found from Somalia in the west to Kazakhstan in the east in desert and semi-desert habitats (Kothe-Heinrich 1993).

This genus belongs to the Salicornioideae and comprises five perennial halophytic species that are distributed in central and southwestern Asia as well as southern and southeasternmost Europe. The monophyly of Kalidium is only weakly supported by molecular data (Kadereit & al. 2006).

The isolated lineage of Chenopodium polyspermum L., revealed in the phylogenetic study of Fuentes-Bazán & al. (2012b), is well supported by the unique morphological characters of that widespread Eurasian species, which led to the creation of a monotypic subsection within Chenopodium s.l. (Mosyakin & Clemants 1996).

A monotypic genus in Salicornioideae of rare hygrohalophytic herbs with two subspecies that show a disjunct distribution in the western and eastern Mediterranean region to central Iran (Kadereit & Yaprak 2008).

A genus of c. ten closely related xerophytic species that are distributed in central Asia (Pratov 1985). Nanophyton is related to Halocharis and Kaviria based on phylogentic studies (Akhani & al. 2007).

Hohmann & al. (2006) showed that this monotypic genus belongs to Betoideae-Hablitzieae. Oreoblitonthesioides is a subshrub distributed on calcareous rocks in Algeria and Tunisia. Together with its sister genus Aphanisma it represents an interesting example of a western Eurasian-western North American disjunction (Kadereit & Baldwin 2012).

Oxybasis was described by Karelin & Kirilov (1841) and included at that time only one species, O. minutiflora Kar. & Kir. (= Oxybasis chenopodioides (F.) S. Fuentes & al.). The phylogenetic studies by Fuentes-Bazán & al. (2012b) and Sukhorukov & al. (2013) supported the monophyly of this widespread genus as a member of Chenopodieae and enlarged its circumscription with species segregated from Chenopodium s.l. At least ten species are currently known (some recently transferred from Chenopodium: see Mosyakin 2013; Sukhorukov 2014), and some occur in saline habitats. Since Oxybasis contains O. rubra (L.) S. Fuentes & al., and its basionym, C. rubrum L., is considered by some authors to be lectotype of Chenopodium, the adoption of that lectotype would result in Oxybasis becoming a synonym of Chenopodium (see there).

According to Kadereit & al. (2006) Patellifolia is a separate genus, more closely related to Habliztia than to Beta. According to Thulin & al. (2010) Patellifolia includes only one polymorphic species within a wide Macaronesian-Mediterranean distribution and a small disjunct eastern African population.

A genus of c. 12 species distributed in saline soils of central and southwestern Asia, westwards to the eastern Mediterranean. Petrosimonia is a typical genus with bifurcate hairs. It forms a monophyletic group with Ofaiston within Caroxyleae (Akhani & al. 2007).

Pyankovia is a recent segregate of Climacoptera and Salsola s.l.; it was initially described as a monotypic genus (Akhani & al. 2007). Further studies showed that the genus contains more than one species (Wen & al. 2010). There are probably at least three species distributed from southeastemmost Europe through the Caspian area, the Caucasus, and Iran to central Asia (S. Mosyakin, unpubl. data).

Salsola s.l. was a heterogenous and polyphyletic complex, which has been split into at least ten lineages based on nuclear and chloroplast markers (Akhani & al. 2007; Pyankov & al. 2001; Kadereit & Freitag 2013). Caroxylon as the largest group, and Climacoptera, Kaviria and Pyankovia were transferred to the tribe Caroxyleae (Caroxyloneae). Several other segregates have either been described as new genera or were resurrected from existing names, including Kali, Turania and Xylosalsola. Three names were informally mentioned: “Canarosalsola”, “Collinosalsola” and “Oreosalsola”, the last soon to be formally published (Akhani & Khoshravesh, in press). The two species, S. webbii Moq. and S. genistoide Juss. ex Poir., are sister of Salsoleae and therefore should be described as separate genera (Voznesenskaya & al. 2013).

The typification of the genus Salsola is debated (Akhani & al. 2014; Mosyakin & al. 2014), and a conserved type, S. kali L., is proposed instead of the current type, S. soda (Mosyakin & al. 2014). If accepted, the name Salsola L. will replace Kali Mill, and Salsola sensu Akhani & al. will be Soda Fourr. In its present circumscription accepted here, Salsola is still a morphologically very diverse group that probably deserves further splitting into several more natural genera, following more comprehensive molecular and morphological studies.

This monotypic genus belongs to Camphorosmoideae, with an annual species distributed from Hungary to southern Siberia and showing a C3/C4 intermediate photosynthetic pathway (Kadereit & al. 2014). The illegitimate name Salsola sedoides Pall. (the basionym of Sedobassia sedoides) was proposed for conservation against Salsola sedoides L. (Freitag & Sennikov 2014). If this proposal is accepted, the name Sedobassia sedoides (Pall.) Freitag & G. Kadereit will remain in use.

Molecular phylogenetic studies clearly show that Alexandra and Borsczowia should be included in a monophyletic Suaeda (Kapralov & al. 2006), despite the arguments by Lomonosova & Freitag (2011), who preferred a paraphyletic Suaeda by keeping Alexandra as a separate genus. The study by Schütze & al. (2003) is currently the most comprehensive molecular and morphological study of the genus. The pollen morphology of Suaeda was studied by Dehghani & Akhani (2009).

Since the treatment of Beck (1907–1909), Teloxys was included and mostly accepted in Chenopodium subsect. Teloxys. For the Flora of North America, Mosyakin & Clemants (2002) transfered this species to Dysphania. However, the phylogenetic studies of Kadereit & al. (2010) and Fuentes-Bazán & al. (2012a) recovered an isolated position of the monotypic Teloxys, supporting its first circumscription (Moquin 1834) and also revealing its close relationship to Cycloloma, Dysphania and Suckleya.

A segregate genus of Salsola s.l. consisting of small or large shrubs occurring in sandy or gravelly habitats of the central Asian and Iranian deserts (Tzvelev 1993; Akhani & al. 2007).

Didiereaceae Radlk, sec. apg (2009).

A family with six genera and 20 species (Bruyns & al. 2014). Traditionally, Didiereaceae included xerophytic shrubs and trees endemic to Madagascar with short lateral shoots bearing spines or alternate leaves (Kubitzki 1993a; Cuénoud 2003). However, molecular phylogenetic studies (Applequist & Wallace 2001, 2003; Nyffeler & Eggli 2010a; Bruyns & al. 2014) showed a well-supported clade including the traditional Didiereaceae plus the African genera Calyptrotheca, Ceraria and Portulacaria, previously placed in Portulacaceae. This expanded circumscription of the family is accepted here, which includes also much-branched plants with opposite leaves and without spines. Applequist & Wallace (2003) divided the family into three subfamilies: Calyptrothecoideae, Didiereoideae (= traditional Didiereaceae) and Portulacarioideae. The recent molecular phytogeny of Bruyns & al. (2014) supports the monophyly of these subfamilies and the inclusion of Ceraria within Portulacaria.

A small family of woody lianas comprising three monotypic genera endemic to the Guineo-Congolian rainforest (Poremski & Barthlott 2003). The family is characterized by leaves with grapnels on branches or paired at the leaf apex, elongated funicles and large discoid and winged seeds (Heubl & al. 2006). The family is considered as partially carnivorous because it includes both carnivorous (Triphyophyllum) and non-carnivorous taxa (Dioncophyllum and Habropetalum). The studies by Heubl & al. (2006) and Renner & Specht (2011) concluded that within Dioncophyllaceae occurred a partial secondary loss of carnivory. See also notes under Ancistrocladaceae.

Droseraceae Salisb. sec. apg (2009).

The family includes perennial or annual carnivorous herbs and sometimes submerged aquatics (Kubitzki 2003b) characterized by having perception of tactile and chemical stimuli, leaf blade and tentacle movement and genetically by a loss of the rpl2 intron (Heubl & al. 2006). The family comprises three genera, two of them monotypic: Aldrovanda distributed in Eurasia, southeastern Africa and northeastern Australia, and Dionaea endemic to the southeastern United States. Drosera is cosmopolitan and comprises probably more than 100 species (Kubitzki 2003b; Rivadavia & al. 2003). The family is well known to attract, capture, retain and digest small prey animals (mainly small arthropods) with active snap-traps (Aldrovanda [waterwheel plant] and Dionaea [Venus flytrap]) or with active sticky flypaper traps (Drosera [= sundews]) and to absorb the resulting nutrients (Poppinga 2013). The relationships of Droseraceae to the other carnivorous families of the Caryophyllales remain unclear; the results of several molecular phylogenetic studies resulted in three main hypotheses: Droseraceae as sister of Nepenthaceae (e.g. Nandi & al. 1998: rbcL; Cuénoud & al. 2000; Brockington & al. 2009: combined nuclear and plastid data; Schäferhoff & al. 2009: petD); Droseraceae as sister of a clade including Drosophyllaceae + [Ancistrocladaceae + Dioncophyllacae] (e.g. Schäferhoff & al. 2009: petD) and Droseraceae as sister of the rest of the carnivorous families (e.g. Meimberg & al. 2000: partial matK;Schäferhoff & al. 2009: complete matK;Renner & Specht 2011: combined nuclear, ribosomal and plastid data).

Drosera has a worldwide distribution, but the majority of species are found in the southern hemisphere, especially in southwestern Australia and New Zealand (Kubitzki 2003b; Rivadavia & al. 2003). Several classifications have been proposed for the genus; the last one was that by Seine & Barthlott (1994), who recognized three subgenera and 11 sections based on morphological, anatomical, palynological and cytotaxonomical characters; the molecular phylogenetic study that included the most representative subgenera and sectional sampling so far (i.e. Rivadavia & al. 2003) supported the monophyly of only some of these groups.

A monotypic family that includes carnivorous subshrubs distributed in Spain, Portugal and Morocco (Kubitzki 2003c). These are characterized by reverse circinate leaves, basal placentation, polyporate pollen and a chromosome base number x = 6 (Heubl & al. 2006). Historically, the single genus Drosophyllum was placed within Droseraceae, but its position as an independent lineage has been well supported by several molecular phylogenetic studies (e.g. Meimberg & al. 2000; Cuénoud & al. 2002; Hilu & al. 2003; Brockington & al. 2009; Schäferhoff & al. 2009). These studies also revealed the closer relationship of Drosophyllacae with the clade Ancistrocladaceae + Dioncophyllaceae rather than Droseraceae.

Frankeniaceae Desv. sec. apg (2009).

A monogeneric family with 70–80 species of halophytic and xerophytic shrubs, subshrubs and herbs (Whalen 1987; Kubitzki 2003d) distributed throughout the warmer dry regions of the world (Kubitzki 2003d). Kubitzki (2003d) recognized two genera: Frankenia and the monotypic Hypericopsis; however in the same year Olson & al. (2003) supported the inclusion of Hypericopsis within Frankenia based on wood-anatomical characters. The position of Hypericopsis within the Eurasian and Australian clade of Frankenia has also been well supported by the molecular phylogenetic study of Gaskin & al. (2004).

Gilbert (1993) revised the genus and accepted seven species; however, Bissinger & al. (2014) found all species to be polyphyletic and suggested to treat them as one polymorphic species or species complex, Gisekia pharnaceoides agg. Gisekia pharnaceoides is a C4 species with atriplicoid Kranz anatomy and NAD-ME biochemical type. The lineage originated in South Africa and presumably migrated along arid areas of eastern Africa during the late Miocene/Pliocene (Bissinger & al. 2014).

A monotypic family of succulent monoecious herbs, endemic to semi-deserts of western and southwestern Argentina (Hunziker 1998; Bittrich 1993c; Pozner & Cocucci 2006). For many years the position of the only species, Halophytum ameghinoi (Speg.) Speg. within Caryophyllales was uncertain. When the species was described, it was placed in Aizoaceae and later transferred to Chenopodiaceae (e.g. Cronquist 1981). Several molecular phylogenetic studies have shown that it represents a well-supported independent lineage within the Portulacineae (Brockington & al. 2009, 2011; Nyffeler & Eggli 2010a; Ocampo & al. 2010; Arakaki & al. 2011), but its relationships with the other families in this group remain uncertain. The most recent phylogenetic study, based on data from several nuclear and chloroplast markers, supports a close relationship between Halophytum and Basellaceae and a close relationship of both with Didiereaceae (Anton & al. 2014).

Eight species, distributed in Africa and Saint Helena; checklist of species in Christenhusz & al. (2014). These species were formerly included in Hypertelis (Molluginaceae), but have been shown to occupy an isolated position in Caryophyllales (Christin & al. 2011).

A monogeneric family with c. 20 species, distributed mainly in southern Africa with a few species in Sudan, Ethiopia and southern Asia (Endress & Bittrich 1993). Traditionally, the single genus Limeum was placed in Molluginaceae. However, the position of the genus as an independent lineage and its distant placement from Molluginaceae has been well supported by several molecular studies (Brockington & al. 2009; Schäferhoff & al. 2009; Christin & al. 2011). The family includes herbs and subshrubs characterized by pseudomonomerous twochambered ovaries (Endress & Bittrich 1993).

Small family of about six species distributed in Africa, mainly in the southwest, and southwestern Asia (Endress & Bittrich 1993; Rohwer 1993). The family includes the genus Lophiocarpus, previously placed in Phytolaccaceae subfamily Microteoideae and the genus Corbichonia, previously placed in Molluginaceae. The clade Lophiocarpus + Corbichonia was first recovered and well supported in the molecular phylogeny based on matK sequences by Cuénoud & al. (2002). The family was described by Doweld and Reveal (2008) and the clade was later confirmed by Schäferhoff & al. (2009) and Brockington & al. (2011). The two genera included in Lophiocarpaceae are morphologically very different. While members of Lophiocarpus are herbs and sometimes suffrutescent, characterized by flowers in spikes (with five tepals and four stamens) and achenes (Rohwer 1993), members of Corbichonia are herbs or subshrubs, characterized by flowers in cymes (with five sepals and several petaloid staminodes and stamens) and capsules (Endress & Bittrich 1993; Boulos 1999; Sukhorukov & Kushunina 2015).

A monogeneric family restricted to the Neotropics and distributed from Central America and the Antilles to South America (Rohwer 1993; Schäferhoff & al. 2009). Based mainly on the presence of single-ovuled ovaries, Nowicke (1969) placed Microtea, together with Lophiocarpus, in Phytolaccaceae subfamily Microteoideae. However, Schäferhoff & al. (2009) showed that these two genera are not closely related and the position of Microtea as an independent lineage was well supported, resulting in the description of the new family. These results were later confirmed by Brockington & al. (2011).

A poorly studied genus of annual herbs from Central and South America and the Antilles. The number of species is estimated to c. 12 (Schäferhoff & al. 2011); a modem monograph is lacking. Microtea was found in an isolated phylogenetic position (Schäferhoff & al. 2011; two species have been sampled).

A family with nine genera and c. 90 species mainly distributed in southern Africa, but also found in the tropics around the world. The circumscription has been problematic and some of the taxa formerly assigned to Molluginaceae are now considered as members of other families (especially Aizoaceae and Phytolaccaceae) or as independent families within the Caryophyllales (e.g. Kewaceae, Limeaceae, Lophiocarpaceae) (Endress & Bittrich 1993; Schäferhoff & al. 2009; Christin & al. 2011; Christenhusz & al. 2014). The family as currently circumscribed is characterized by an undifferentiated perianth with alternitepalous stamens, except for Glinus, which occasionally has small petals (Brockington & al. 2013).

Recent phylogenetic analysis has shown that the genus is not monophyletic and that its species are scattered across the Molluginaceae phytogeny (Christin & al. 2011). A thorough re-evaluation of the circumscription of Mollugo is clearly needed.

monotypic; endemic to the subantarctic Kerguelen Islands. Lyallia kerguelensis was found to be sister to Hectorella and both are nested in Montiaceae (Wagstaff & Hennion 2007; see also under Hectorella).

Based on phylogenetic analyses (Hershkovitz 1996), Hershkovitz (1998) transferred 35 Australian Calandrinia species to the new genus Parakeelya. However, the relationships of the species of this genus within Montiaceae are not well supported (Hershkovitz 1996; Hershkovitz & Zimmer 2000), so further studies are needed to evaluate its affinities. Australian botanists still continue to use the name Calandrinia for species assignable to Parakeelya. The relationships of the Australian genus Rumicastrum are not clear. It was considered as a genus closely related to Atriplex (Chenopodiaceae). Carolin (1987) and Hershkovitz (1993) used the name to represent the Australian calandrinias (Montiaceae); however, Hershkovitz & Zimmer (2000) opted to use the name Parakeelya for those taxa. Further studies are required to clarify the correct use of Rumicastrum.

An enigmatic monotypic genus, placed here with doubts, and not included in any recent analysis.

Nepenthaceae Dumort. sec. apg (2009).

A monogeneric family comprising 120–138 species (McPherson 2009, 2011) native to tropical Asia, distributed from Madagascar through Indo-Malesia to New Guinea and New Caledonia (Kubitzki 2003e; Meimberg & Heubl 2006). The family includes woody climbers or scrambling shrubs and some epiphytes (Kubitzki 2003e) widely known as the carnivorous “pitcher plants”. They are characterized by unisexual flowers, axilar placentation, filaments united into a column, three- or four-locular ovaries and the loss of vascularization in glands (Heubl & al. 2006). The affinities of Nepenthaceae have long been discussed (Meimberg & al. 2001). Traditionally, the family was placed in the order Nepenthales, either as a monofamilial order (e.g. Takhtajan 1980) or together with Droseraceae and Sarraceniaceae (e.g. Cronquist 1988). The placement of the family within Caryophyllales was shown by the early molecular phylogenetic study of Nandi & al. (1998). Several molecular phylogenetic studies have shown (although with moderate support) the close relationship of Nepenthaceae and Droseraceae (Nandi & al. 1998; Cuénoud & al. 2000; Brockington & al. 2009; Schäferhoff & al. 2009; further information under Droseraceae). Another study, based on parsimony analysis of combined rbcL and matK shows with high support Nepenthes as sister to the rest of the carnivorous families, whereas the study of Renner & Specht (2011), based on the ML and Bayesian analysis of the combined data of nuclear, ribosomal and plastid DNA, shows also with high support the relationship of Nepenthaceae with the Drosophyllaceae + [Dioncophyllaceae + Ancistrocladaceae] clade.

This family comprises c. 30 genera and 300–400 species (Bittrich & Kühn 1993; Spellenberg 2003) of trees, shrub and herbs. These are found in all warmer areas of the world (Douglas & Spellenberg 2010), but mostly in the Americas, with two centres of distribution: arid western North America (southwestern U.S.A. and northern Mexico) and the Neotropics (tropical and subtropical South America and the Antilles). Some genera, such as Boerhavia, Mirabilis and Pisonia, have some species occurring in the Old World, but some of them are introduced (Mirabilis), whereas Commicarpus, with few American species, is most diverse in Africa; Phaeoptilum is endemic to southwestern Africa and Botswana (Bittrich & Kühn 1993; Douglas & Spellenberg 2010). Recently, Douglas & Spellenberg (2010), based on the molecular phytogeny of the family by Douglas & Manos (2007), made some adjustments to Bittrich and Kühn's classification of 1993, so that seven tribes were recognized: Boldoeae, Bougainvilleeae, Caribeeae, Colignonieae, Leucastereae, Nyctagineae and Pisonieae; the relationship of Caribeeae with the others is unknown since it is known only from the type. Several genera, especially those of North America that include the suffrutescent and herbaceous taxa, have been the focus of interest of various studies. However, most of the taxa distributed in the Neotropics, including the trees and shrubs in the diverse genera Guapira, Neea and Pisonia, are poorly known.

Boerhavia, with c. 40 species, is distributed in warmtemperate and tropical regions worldwide (Spellenberg 2003) and has been recognized as a natural group by Douglas & Manos (2007). Several authors (Fay 1980; Spellenberg 2001, 2003) have highlighted that at the species level this is a taxonomically difficult group due to morphological variation. Especially among annuals of the Sonoran desert and the pantropical B. diffusa Vahl and B. coccinea Mill, complex (Spellenberg 2001, 2003), apparently factors such as wide dispersal, hybridization and autogamy have contributed to that variation (Fay 1980; Spellenberg 2001, 2003). The genus is in need of a critical revision.

The genus is monotypic, with B. purpurascens Cav. ex Lag. distributed from Mexico and the Antilles to northern South America. Along with Cryptocarpus and Salpianthus, Boldoa is placed within the tribe Boldoeae (Douglas & Spellenberg 2010), and in several treatments (Standley 1911, 1918, 1931; Fay 1980; Pérez & al. 2000; Spellenberg 2001; Hernández-Ledesma & Flores 2003; González 2007) the genus has been included in the wide concept of the genus Salpianthus. Here we follow Bittrich & Kühn (1993) and Harling (2010), who consider them as separate genera because of differences of the perianth: Boldoa has a campanulate perianth (2–3.5 mm long) with glandular and uncinate hairs, Salpianthus has a tubular perianth (6–7 mm long) with straight hairs, while Cryptocarpus has a pyriform perianth (1.5–2 mm long). A revision and phylogenetic analysis including all the species of the tribe is necessary to evaluate the circumscription of the genera.

Standley and Steyermark (1946) state that Bougainvillea contains c. 14 species native to South America, three of which were cultivated in tropical and subtropical regions of the world. According to Fay (1980), the genus includes ten species, but that author argued that artificial selection processes, hybridization and the spread of clonal variants have produced a complex pattern of variation only loosely related to any natural group. Gillis (1976) treated the bougainvilleas of cultivation, considering three species and one hybrid. The biology, artificial selection as well as the lack of a monographic treatment make it difficult to determine the current number of species.

An endemic genus from Cuba that has a unique morphology among the Nyctaginaceae (Douglas & Spellenberg 2010). Caribea includes compact bushforming taprooted perennials characterized by opposite leaves forming a stipulariform sheath at the base (Bittrich & Kühn 1993; Douglas & Spellenberg 2010). Because the genus is known only from the type collection, the most recent classification system for the family (Douglas & Spellenberg 2010) included it in its own tribe, Caribeeae. It is awaiting its rediscovery in the field.

A neotropical genus with c. 70 species, distributed from southern Florida to South America and the Antilles. It is closely related to Neea, also being dioecious and having fleshy fruits. Both genera form a complex and their distinctness has been questioned by several authors (e.g. Standley 1931; Burger 1983; Pool 2001; Douglas & Manos 2007) because they are distinguished only by the presentation of the stamens, which are included in Neea and exserted in Guapira. In the phylogenetic analysis by Douglas & Manos (2007), the two genera form a clade in which both are paraphyletic; however those authors questioned if this result was the effect of their sampling (Guapira, two species; Neea, three species) or whether the paraphyly is due to the lack of resolution between both genera. Guapira needs a taxonomic revision and also needs to be evaluated in a phylogenetic analysis that includes an extensive sampling along with Neea.

A genus with 50–60 American and one Asiatic species. It includes herbs, suffrutescent herbs and subshrubs characterized by the presence of involucres of accrescent bracts, often connate, which surround one or more flowers. Traditionally the genus was classified into six sections, some of them corresponding to previously separated genera. Molecular phylogenetic studies, which have mainly been focused on the North American species, support the monophyly of the genus (Levin 2000; Douglas & Manos 2007; P. Hernández-Ledesma & al., unpubl. data) but not the monophyly of the sections (P. Hernández-Ledesma & al., unpubl. data). In order to achieve a natural subgeneric classification, the South American species should be included in the sampling.

Neea shows extensive morphological variation in habit, leaves, pubescence, inflorescences, flowers and fruits (Burger 1983). Some authors (e.g. González 2007) have considered it the taxonomically least understood group in the Neotropics. Neea seems to be the most species-rich genus within Nyctaginaceae; Douglas & Spellenberg (2010) mentioned that the genus has c. 80 species. However, the lack of a revision, along with the morphological variation and dioecy, has generated many species names (c. 150), whereas the actual number of species remains uncertain. For further information see notes under Guapira.

This genus includes shrubs, trees and woody climbers characterized by stout spines on the stems and coriaceous fruits with stipitate glands. Its distribution is pantropical with a centre of diversity in the Neotropics. Molecular phylogenetic studies (e.g. Douglas & Manos 2007; León de la Luz & Levin 2012) supported the monophyly of Pisonia, although the genus was poorly sampled in both studies. Pisonia has not been monographed, and the number of species is uncertain; some treatments considered 40 species (e.g. Spellenberg 2001; DeFilipps & Maina 2003; González 2007) whereas others (e.g. Spellenberg 2003) considered a range between 10–50 species; in the literature there are numerous accepted and unresolved names.

The genus includes shrubs with alternate leaves, a four- or five-lobed tubular petaloid perianth with straight glandular hairs, three to four long-exserted stamens and a linear style (Bittrich & Kühn 1993). Three species are recognized following this concept: S. aequalis Standi., S. arenarius and S. macrodontus Standi., all of them with restricted distributions in Mexico. Salpianthus was assumed to be monophyletic by Douglas & Manos (2007); however, only S. arenarius was included in their study. For further information see notes under Boldoa.

A monogeneric family with two species endemic to Madagascar (Dickison 2003). Traditionally, the only genus Physena was placed in Capparales/Capparaceae (e.g. Pax & Hoffmann 1936) or Flacourtiaceae (e.g. Perrier de la Bâthie 1946). Later, it was considered as a family of its own and placed in the order Sapindales (e.g. Takhtajan 1980, 1987) and was then even transferred to the separate order Physenales (e.g. Takhtajan 1997). However, already the early molecular phylogenetic studies of Morton & al. (1997) showed the affinities of Physenaceae with Caryophyllales and its close relationship to Asteropeiaceae. These results were confirmed by subsequent molecular phylogenetic studies (e.g. Cuénoud & al. 2002; Brockington 2009, 2011; Soltis & al. 2011). The relationship between Asteropeiaceae and Physenaceae is also supported by wood-anatomical characters. For further information see notes under Asteropeiaceae.Physena Noronha ex Thouars in Gen. Nov. Madagasc.:

Phytolaccaceae R. Br. sec. apg (2009).

This family comprises herbs, trees or lianas distributed mainly in the Americas, including the Antilles, but with some members distributed in Australia and New Caledonia. They are characterized by styloids, elongate crystals, racemes or spikes and four or five tepals (Rohwer 1993a; Stevens 2001 onwards). The circumscription of the family has long been controversial. Following the treatment by Rohwer (1993a), Phytolaccaceae have been disintegrated step by step according to the results of molecular phylogenetic studies (e.g. Cuénoud & al. 2002; Hilu & al. 2003; Schäferhoff & al. 2009; Brockington & al. 2011), which have shown that the subfamilies Agdestioideae, Barbeuioideae and Microteoideae (sec. Rohwer 1993a) are well-supported independent lineages. Therefore, these taxa are now treated at family level (see further notes under those families). These studies have also shown that Phytolaccaceae s.l. comprising the subfamilies Phytolaccoideae and Rivinoideae (sec. Rohwer 1993a) are not monophyletic. The most recent study by Brockington & al. (2011) included most of the genera recognized in these subfamilies and showed that the Phytolaccoideae (= Phytolaccaceae s.str.) represents a well-supported independent lineage, while the support for Rivinoideae is present but weak. Recent studies (J. Petersen, T. Borsch & P. Hernández-Ledesma, unpubl. data) show that the latter is probably more closely related to Nyctaginaceae than to Phytolaccaceae s.str. Rivinaceae have been recognized as an independent family within Caryophyllales by Stevens (2001 onwards). However, the correct family name for a clade that includes the genera Petiveria and Rivina would have to be Petiveriaceae C. Agardh (1824) and not Rivinaceae C. Agardh (1824). Both family names were published in the same work (Agardh 1824) but Meissner (1836) included Rivina under Petiveriaceae separate from Phytolaccaceae. This gives priority to Petiveriaceae. The taxon has a complicated taxonomic history. In some early treatments members were classified either within Phytolaccaceae and distinct from Petiveriaceae C. Agardh (Lindley 1853), or vice versa (e.g. Hutchinson 1959; Brown & Varadarajan 1985), or at an infrafamiliar or infrageneric level within Phytolaccaceae (e.g. Petiverieae, Rivineae, Rivinoideae) (including Petiveria and related genera) (e.g. Heimerl 1889, 1934; Rohwer 1993a).

Phytolacca comprises 25–35 species of perennial herbs, shrubs and trees distributed in North and South America, eastern Asia and New Zealand. The genus Nowickea is here included; it was characterized by a well-developed gynophore, green herbaceous and often elongated tepals and obovoid or obpyriform fruits with narrowly ellipsoid seeds (Martínez & McDonald 1989). Since its publication, the genus was known only from the type and considered as distinct from Phytolacca. However, Cruz & Alcántara (2000) described several anomalous characteristics in P. icosandra L. and showed similarities with Nowickea. Recently, Ramírez-Amezcua & Steinmann (2013) showed that the Nowickea species correspond to anomalous plants of P. icosandra: the evidence was based on specimens showing the characteristic flowers of P. icosandra along with anomalous flowers (in one plant) showing the distinctive characteristics of Nowickea.

Plumbaginaceae Juss. sec. apg (2009).

A cosmopolitan family of perennial herbs or shrubs, rarely climbers, mainly distributed in the temperate zones of the northern hemisphere, especially in the Mediterranean and Irano-Turanian regions but also in southern Africa, southern South America and Western Australia. The family comprises 25–30 genera and 650–1000 species, which predominantly occur in arid and saline environments and often in coastal habitats. The family is characterized by flowers that have stamens opposite the petals and a single basal anatropous ovule with a curled funicle. Molecular studies based on different markers have shown that Plumbaginaceae are well supported as monophyletic family within Caryophyllales and sister to Polygonaceae (e.g. Cuénoud & al. 2002; Hilu & al. 2003). Lledó & al. (1998, 2001) confirmed the classification of Plumbaginaceae into two subfamilies, Limonioideae and Plumbaginoideae, well differentiated by morphological, chemical and molecular characters. Plumbaginoideae are mostly distributed in the pan tropical region and comprise four genera; Plumbago with c. 20 species is the largest. Limonioideae have diversified in regions with a Mediterranean climate and are morphologically more diverse. This sub-family is divided into two tribes: Aegialitideae (one genus with two species) and Limonieae. Most species of Limonieae (> 85%) are grouped into three genera: Acantholimon, Armeria and Limonium, while the remaining species belong to monotypic or small genera (Kubitzki 1993b) mostly segregated from Acantholimon and Limonium. The status of most of these genera is unclear; generic concepts and relationships are in need of revision.

A large genus of cushion-forming subshrubs; 150–200 species (including many narrow endemics) distributed from southeastern Europe to central Asia, centred in the mountainous regions of Turkey, Iran and Afghanistan (Kubitzki 1993b). The study by Lledó & al. (2005) included only one representative of Acantholimon, which was recovered in a clade together with Cephalorhizum and Dictyolimon. Moharrek & al. (2014) studied 50 species Acantholimon from Iran. Due to the unresolved position of Cephalorhizum turcomanicum Popov (found either as sister to Acantholimon or nested within it), monophyly of Acantholimon is uncertain. Old sections of Acantholimon were not found as monophyletic (Moharrek & al. 2014).

Afrolimon Lincz. in Novosti Sist. Vyssh. Rast. 16: 168. 1979 sec. Kubitzki (1993b). — Type: Afrolimon peregrinum (P. J. Bergius) Lincz. A group of about ten species from the Cape region of South Africa. Two representatives sampled by Lledó & al. (2005; A. peregrinum, A. purpuratum Lincz.) were found nested within Limonium. According to these results, the status as a distinct genus can not be maintained.

Ceratolimon, a segregate from Limoniastrum, includes four species of dwarf shrubs with disjunct distributions on the Atlantic and Indian Ocean edges of the Sahara Desert (Crespo & Lledó 2000). Three species sampled by Lledó & al. (2000) formed a well-supported clade, that is sister to Limoniastrum.

Four species distributed in Afghanistan, Pakistan, and India. One representative was sampled (D. macrorrhabdos) and found in a clade together with Acantholimon acerosum (Willd.) Boiss. and Cephalorhizum coelicolor (Rech. f.) Rech. f. (Lledó & al. 2005).

The largest genus of the family with an estimated c. 350 species with a preference for coastal habitats; distributed worldwide but mainly in the Mediterranean region. Afrolimon was shown to be nested in Limonium and related to L. vulgare, the type of Limonium (Lledó & al. 2005). Limonium is divided into two major clades corresponding to subgenera, but otherwise the current infrageneric classification proved to be artificial (Lledó & al. 2005). Akhani & al. (2013) studied the Irano-Turanian taxa of Limonium. They stated that segregation of Eremolimon is not supported by morphology or molecular data (Akhani & al. 2013). Evolutionary studies of this group are complicated by hybridization, many microspecies and apomictic taxa.

Monotypic genus; distributed in the western Sahara Desert. Segregated from Limoniastrum based on results from Lledó & al. (2000); was found in a clade together with Armeria-Psylliostachys, Bakerolimon and Myriolimon (Lledó & al. 2005).

The Polygonaceae are a morphologically diverse clade containing more than 50 genera and 1200 species. The family is a monophyletic group with the morphological synapomorphies of an ocrea, orthotropous ovules, (usually) trigonous achenes and quincuncial aestivation (Judd & al. 2007). Polygonaceae are distributed worldwide and are present in almost all ecosystems ranging from tropical rainforests to alpine regions and tundra (Brandbyge 1993; Sanchez & al. 2009). Burke & Sanchez (2011), based on phylogenetic data, recognized three subfamilies: Eriogonoideae, Polygonoideae and Symmerioideae. Polygonoideae were considered non-monophyletic in previous studies (Lamb Frye & Kron 2003; Sanchez & Kron 2008), but a new circumscription by Sanchez & al. (2011) supported a monophyletic subfamily including the type genus Polygonum and other genera such as Atraphaxis, Fagopyrum, Fallopia, Koenigia, Muehlenbeckia, Oxyria, Persicaria, Rheum and Rumex; whereby Eriogonoideae was expanded to include currently recognized Antigonon, Coccoloba, Ruprechtia, Triplaris and other members of the woody genera previously included in Polygonoideae (Sanchez & Kron 2009; Burke & al. 2010). It is important to mention that much work is still needed within the tribe Eriogoneae (or Eriogonoideae s.str.), since most of the recognized genera have no support as being monophyletic (Kempton 2012). Symmerioideae is monotypic and the only species recognized is Symmeria paniculata Benth.; this subfamily shows a unique trans-Atlantic disjunction, in the Amazon Basin and western Africa, which needs further study (Burke & Sanchez 2011).

The genus Antigonon, with three to six species, consists of woody or herbaceous perennial lianas that grow in Mexico and Central America, with the exception of A. leptopus Hook. & Arn., which is widely cultivated as an ornamental (Brandbyge 1993). Sanchez & Kron (2009), Sanchez & al. (2009), Burke & al. (2010) and Burke & Sanchez (2011), based on consistent and highly supported molecular data, proposed that Antigonon and Brunnichia, two genera with suffrutescent habit and tendril-bearing lianas, are clearly distinguished from the rest of the subfamily Eriogonoideae. According to Brandbyge (1993), the described species are poorly defined and a taxonomic revision is needed.

= Guaiabara Mill., Gard. Dict. Abr., ed. 4: [590]. 1754. Coccoloba includes c. 120 Neotropical species, which are grouped in four areas with distinguished endemism: the Antilles, Central America, northern South America and the Amazon region of Brazil (Stohr 1982; Brandbyge 1993). The presence of an ocrea (also ochrea), flowers with five tepals and eight stamens and the globose or trigonous achenes are the fundamental characteristics that support the relationships among Coccoloba, Neomillspauhia and Podopterus (Sanchez & Kron 2009; Burke & al. 2010; Burke & Sanchez 2011). The particular ecological conditions and ecological isolation of the Antilles allow inferring a radiation, mainly in Cuba and Hispaniola, with c. 40 endemic species; however, there is no biogeographic hypothesis for the genus. Currently, Coccoloba is classified in several sections, which have not been phylogenetically evaluated.

A new genus segregated form Muehlenbeckia, based on the molecular study by Schuster & al. (2011). The genus comprises three species restricted to Australia, and is characterized by erect shrubs with thornlike branches. This habit it not found in any other Muehlenbeckia (as studied by Schuster & al. 2011). In addition, Duma does not possess extrafloral nectaries at the petiole base, which are present in most species of Fallopia, Muehlenbeckia and Reynoutria.

This genus has been considered as a synonym of Fagopyrum, based on pollen morphology (Hong 1988). However, recent molecular analyses did not place it in Fagopyrum (Ohsako & al. 2001; Galasso & al. 2009; Sanchez & al. 2011). Since there are morphological characters that suggest placement in Fagopyrum, but no molecular evidence for that relationship, Eskemukerjea was left as incertae sedis by Sanchez & al. (2011).

The genus Gymnopodium was originally described with three species, growing as shrubs or small trees on limestone soils in Belize, Guatemala, and the Yucatán Peninsula in Mexico (Blake 1921; Brandbyge 1993). Sanchez & al. (2009) and Burke & al. (2010) showed that Gymnopodium is strongly supported as monophyletic in the subfamily Eriogonoideae (sec. Burke & Sanchez 2011); based on leaf shape and pubescence characters, the genus should be recognized with only one polymorphic species (Burke & Sanchez 2011).

Leptogonum is an interesting genus of small trees or shrubs, endemic to Hispaniola (Liogier 1983; Brandbyge 1989). In Burke & al. (2010), this genus was placed in the subfamily Eriogonoideae and recognized as its own subtribe Leptogoneae (Burke & Sanchez 2011), based on the lack of accrescent tepals in the fruit, the reduction to three stamens, and the leaves clustered at the stem apices.

This recently published genus comprises two species distributed in Brazil, Bolivia and Venezuela, and it was segregated from Ruprechtia based on molecular and morphological characters (Sanchez & Kron 2011). Magoniella is characterized by a strict lianaceous habit, and it shares with Salta and Triplaris the presence of a scar at the base of the perianth in the fruit.

With only two recognized species, the genus is restricted to the dry forests of Mexico and Central America (Brandbyge 1993; Burke & al. 2010). Previous to their assignment to a new genus by Blake (1921), species of Neomillspaughia had been placed in either Campderia Benth. (Donnell Smith 1899) or Podopterus (Gross 1913). Roberty & Vautier (1964) included Neomillspaughia in the genus Podopterus; however, based on molecular data, Neomillspaughia receives strong support as sister to Coccoloba (Sanchez & al. 2009; Burke & al. 2010).

Oxygonum comprises c. 35 species and is confined to the African continent and Madagascar (Graham 1957; Ortiz & Paiva 1999). Several studies have placed the genus in Polygoneae (Haraldson 1978; Brandbyge 1993; Hong & al. 1998; Galasso & al. 2009); however, Haraldson (1978) suggested a close affinity to Fagopyrum and genera in Rumiceae. Rouse Decraene & Akeroyd (1988) suggested an affinity with Polygonum. Oxygonum has not been sampled in any molecular study; therefore it was left as incertae sedis by Sanchez & al. (2011).

Podopterus Bonpl., Pl. Aequinoct. 2: 89. 1812 sec. Brandbyge (1993). — Type: Podopterus mexicanus Bonpl. Podopterus includes three species restricted to Mexico and Guatemala (Brandbyge 1993). The genus has strong morphological affinities to Neomillspaugia and Coccoloba, based on habit and the presence of five tepals (Burke & al. 2010). Although the placement of Podopterus is not well supported, Burke & Sanchez (2011) included the genus in the tribe Coccolobeae alongside Coccoloba and Neomillspaughia. Neomillspaughia and Podopterus share the presence of accrescent and membranous inner tepals (Blake 1921; Roberty & Vautier 1984).

A monotypic genus distributed in Afghanistan, Pakistan, India and China (Qaiser 2001). The taxonomy of Rubrivena is complex; its members have been included in Polygonum (P. polystachyum;Li & al. 2003) and Persicaria (P. wallichii;Freeman 2005), and both names are accepted by Tropicos (undated). However, based on molecular studies, the placement of Rubrivena is strongly supported as sister to Aconogonon and Koenigia (Sanchez & al. 2011).

A new monotypic genus described in Sanchez & Kron (2011), based on morphological and molecular data. This genus is commonly found in Argentina, Bolivia, Brazil and Paraguay, and is characterized by a pronounced development of brachyblasts and the short axis of the inflorescences borne on a short shoot (Pendry 2004; Sanchez & Kron 2011). Molecular studies have strongly supported the placement of this genus as sister of a clade that includes Magoniella, Ruprechtia and Triplaris (Burke & al. 2010; Sanchez & Kron 2011).

Although the circumscription of the genus has been relatively stable, the infrageneric classification remains controversial. Previous proposals (von Poellnitz 1934; Legrand 1958; Geesink 1969) are only in part consistent with the results of a recent phylogenetic analysis (Ocampo & Columbus 2012). The genus is monophyletic and has two main lineages: one whose members have opposite leaves (OL clade) and are distributed in Africa, Asia and Australia (except P. quadrifida L., which is a pantropical weed), and a second lineage whose species have alternate to sub-opposite leaves (AL clade), are more widespread and originated in the New World. These major clades and their subclades have anatomical and morphological features (Ocampo & Columbus 2012; Ocampo & al. 2013) that will be used to amend the classification of Portulaca.

A monogeneric family comprising three species distributed in tropical South America, the Guyanas, the Amazonian region and northeastern Brazil (Prance 2003). The family has had a complicated taxonomic history. Traditionally, species that are now placed in Rhabdodendron were included in different families of Rutales, in the family Chrysobalanaceae (as the genus Lecostemon DC.) (Bentham 1853) or in Rutaceae (Gilg & Pilger 1905; Huber 1909; Takhtajan 1980). In other systems (e.g. Cronquist 1981), Rhabdodendron was placed within Rosales (for a detailed taxonomic history until the 1970s see Prance 1972). Based on morphological, palynological and anatomical characters, Prance (1972) considered Rhabdodendron in its own family, and suggested for the first time some affinities with Caryophyllales, specifically with Phytolaccaceae. Later on, the early molecular phylogenetic study of Fay & al. (1997) confirmed the affinities of Rhabdodendraceae with Caryophyllales. Since then, the position of the family within the order was also confirmed by subsequent studies (e.g. Cuénoud & al. 2002; Hilu & al. 2003; Schäferhoff & al. 2009; Brockington & al. 2009, 2011; Qiu & al. 2010; Soltis & al. 2011), although there are several hypothesis about its internal position.

A monogeneric family with two species distributed in North America (Kühn 1993; Hils & al. 2003), from the western United States to northwestern Mexico. The family includes shrubs characterized by having thorny branches, ebracteolate and unisexual flowers, staminate flowers arranged in spikes, whereas the pistillate ones are solitary (Wels & al. 2003). Traditionally, the only genus, Sarcobatus, was placed in Chenopodiaceae (for a detailed taxonomic history until the 1990s see Behnke 1997). The early molecular phylogenetic study by Downie & al. (1997) supported the position of Sarcobatus as an independent lineage. In this study, Sarcobatus showed a close relationship with members of Nyctaginaceae and Phytolaccaceae rather than Chenopodiaceae. Based on these results in addition to characters of the sieveelement plastids and some morphological characters, Behnke (1997) described the new family; nevertheless, some authors continued to treat the genus as part of Chenopodiaceae (e.g. Hils & al. 2003). The position of Sarcobatus as an independent lineage was confirmed by other molecular phylogenetic studies (e.g. Cuénoud & al. 2002; Hilu & al. 2003; Brockington 2009, 2011; Soltis & al. 2011; Schäferhoff & al. 2009), which showed a close but only moderately supported relationship of the family with Agdestidaceae.

A monotypic family native to the Sonoran Desert of northwestern Mexico and to neighbouring regions in Arizona and southern California (Vázquez Yanes & al. 1999); it is also introduced in some countries of South America, Europe, Asia and Africa. The family includes evergreen dioecious shrubs with opposite and thick leaves, clearly articulated near the stem; the staminate flowers are small and borne in terminal inflorescences, while the pistillate flowers are single and axillary; the calyx is much enlarged in fruit (Stevens 2001 onwards; Köhler 2003). Traditionally, the family was placed in Hamamelidales (sensu Takhtajan 1980), Euphorbiales (sensu Cronquist 1988) or in its own order Simmondsiales (sensu Takhtajan 1997), in some cases within Buxaceae or close to it. However, the early molecular phylogenetic study by Fay & al. (1997) showed the affinities of Simmondsiaceae with Caryophyllales: this agrees also with several morphological characters of the stylodia, calyces and secondary growth (Köhler 2003). The affinities of the family with Caryophyllales were confirmed by subsequent molecular phylogenetic studies (e.g. Cuénoud & al. 2002; Brockington 2009, 2011; Soltis & al. 2011), which showed that Simmondsiaceae are closer to Rhabdodendraceae and/or to the remainder of the caryophyllid clade. For further information see notes under Rhabdodendraceae.

The only species, Simmondsia chinensis C. K. Schneid., is known as a dominant shrub in its native distribution area. The species is well appreciated for the liquid wax, extracted from the seeds, which is used mainly in the cosmetic industry (jojoba; Vázquez Yanes & al. 1999).

A monogeneric family with three species occurring from northwestern Mexico to Nicaragua and the Antilles (Rohwer 1992). The family includes small trees and shrubs characterized by bisexual flowers with a two-whorled perianth, one whorl consisting of five free green sepals, and the other whorl of five white narrow-based petals adherent to the alternisepalous stamens at the base. The fruits are capsules and the seeds are arillate (Rohwer 1993). When the only genus, Stegnosperma, was described in 1844, it was placed in Phytolaccaceae and accepted by other authors (e.g. Heimerl 1934). Nakai (1942) elevated the genus to the family level. Recognition as a family was also supported by morphological, palynological and wood-anatomical characters (e.g. Nowicke 1969; Bell 1980; Carlquist 1999). For a detailed taxonomic history until the 1980s see Bell (1980). The early molecular phylogenetic studies of Downie & al. (1997) and Fay & al. (1997) showed the position of Stegnosperma as an independent lineage. However, both classifications, the recognition of Stegnospermataceae (e.g. Rohwer 1993; Takhtajan 1997) and Stegnosperma within Phytolacacceae (e.g. Stevens 2001), continued to be used. Subsequent phylogenetic studies (e.g. Savolainen & al. 2000; Cuénoud & al. 2002; Schäferhoff & al. 2009; Qiu & al. 2010; Brockington 2009, 2011; Soltis & al. 2011) confirmed the findings of Downie & al. (1997) and Fay & al. (1997), resulting in the wide recognition of Stegnospermataceae as a separate family.

A family with three genera and around 28 species mainly distributed in Africa, but with a few taxa in the Americas and the tropics around the world (Nyffeler & Eggli 2010a). The species of this family are traditionally considered as members of Portulacaceae; however, molecular phylogenetic studies have shown that the traditional Portulacaceae are not monophyletic (Hershkovitz & Zimmer 1997; Applequist & Wallace 2001; Nyffeler 2007; Nyffeler & Eggli 2010a; Ocampo & Columbus 2010). Nyffeler & Eggli (2010a) proposed the segregation of the traditional Portulacaceae into four families (Anacampserotaceae, Montiaceae, Portulacaceae and Talinaceae) based on morphological and molecular data.

Five genera and c. 80 species occurring in Africa, Asia and Europe with major distribution in the Irano-Turanian and Mediterranean regions (Gaskin 2003). Phylogenetic studies support the monophyly of the genera. Three well-supported clades have been recovered: Hololachna and Reaumuria; Myricaria and Myrtama; and Tamarix. Tamarix is sister to the clade comprising Myricaria and Myrtama, and this group is sister to Hololachna and Reaumuria (Gaskin & al. 2004). The main feature in most genera of Tamaricaceae is the presence of salt glands, which enable successful growth in salty and riparian habitats.

Myricaria is a hygrophytic genus with c. 13 species occuring in Europe and central Asia. Molecular phylogenetic studies support a sister group relationship between Myrtama and Myricaria (Wang & al. 2009).

Tamarix with c. 60 species is most diversified in saline and wet habitats of the Old World and is naturalized in Australia and the Americas, sometimes as aggressive invasive plants. It is one of the few lineages in Caryophyllales that contain large trees and shrubs with a significant role in carbon sequestration and vegetation under harsh and salty conditions. The taxonomy and phylogenetic reconstruction of Tamarix are challenging due to the absence of reliable constant characters and the occurrence of hybridization even among morphologically very different species (Gaskin & Kazmer 2009; Mayonde & al. 2015; Samadi & al. 2013; H. Akhani & T. Borsch, unpubl. data).

Incertae sedis

Listed as a “doubtful genus” in the Caryophyllaceae by Bittrich (1993c).

Summary: current knowledge, trends, gaps

Phylogenetic sampling as a basis for classification

The synopsis of the genera currently accepted in Caryophyllales along with a discussion on the recent work dealing with these genera provides a comprehensive source of information on the current knowledge of this group of plants. In the context of global undertakings, such as the World Flora Online (WFO; CBD-SBSTTA 2012), this study forms the basis for a gap analysis on the availability of treatments for a major group of flowering plants. The results indicate that there is a substantial taxonomic turnover when comparing the current classification with generic concepts available in the complete treatment of the order in Kubitzki's “Families and genera of vascular plants” (FGVP; Kubitzki & al. 1993; Kubitzki & Bayer 2003; Table 2). The number of families has increased substantially (27 vs 39 families), reflecting changes necessary because families were not monophyletic (e.g. Portulacaceae). In addition, several isolated lineages have been recovered that were consequently elevated to family rank (e.g. Kewaceae, Macarthuriaceae). The most diverse families in terms of numbers of genera are the Cactaceae, Aizoaceae, Chenopodiaceae and Caryophyllaceae (all with over 100 genera), while 28 families comprise only one to six genera (Table 2). At the generic level, the numbers have increased by more than ten percent in comparison to the last complete treatments in the FGVP volumes (Table 2). While the number of genera has remained equal (or nearly so) in 18 families, generic boundaries have changed dramatically in some families, especially in Cactaceae and Caryophyllaceae.

It is also clear that sampling at the species level is far from complete, so that many genera or entire tribes lack data needed to assert their monophyly and/or their exact position in the families, while others are already known to be polyphyletic but are insufficiently sampled to be reclassified. In addition, for many taxa no taxonomic revision is available or the existing one is clearly outdated.

For example, in the Aizoaceae of South Africa, 55 % of taxa are in need of revision, 52 % of the recognized taxa in the family have not been treated in any revision, with an additional 12 % of taxa revised prior to 1970 (von Staden & al. 2013). In the Ruschioideae the five largest genera, Ruschia (206 species), Lampranthus (194 species), Delo sperma (142 species), Drosanthemum (107 species) and Antimima (96 species) have never been comprehensively revised at species level (i.e. there is no key to the species). The same is true for numerous smaller genera such as Stomatium (39 species), Hereroa (27 species) and Malephora (16 species). In addition, a recent extensive phylogenetic study of Ruschieae, the most speciose clade in Aizoaceae, showed that numerous genera are not monophyletic, including the large genus Ruschia (Klak & al. 2013). Despite the lack of resolution in parts of the tree due to the lack of variable gene regions, the many cases of polyphyly detected in the phylogeny were an indication of misplaced taxa and narrow generic concepts upheld by traditional taxonomists (Klak & al. 2013). In particular, mono- and bitypic genera in Ruschieae, which were found to be nested within larger genera, need critical re-evaluation (Klak & al. 2013). In contrast, for the Mesembryanthemoideae a phylogeny is available with an almost complete sampling of species (Klak & al. 2007) as well as detailed morphological studies and revisions published for most clades over the last 30 years (e.g. Bittrich 1986; Klak & Linder 1998; Klak & al. 2006; Gerbaulet 1995, 1996a–c, 1997, 2001). However, a conflict in genus delimitaton has erupted between taxonomists with regard to the number of genera that should be recognized in Mesembryanthemoideae. Whereas Klak & Bruyns (2013) favoured a generic concept based on monophyly, Gerbaulet (2012) supported the traditional system of “many genera”, which upholds also genera shown to be paraphyletic (e.g. Phyllobolus). No detailed phylogeny is available for the Aizooideae, which include c. 108 species in seven genera. Finally, a further phylogeny including 18 species from Tetragonioideae indicated that several genera, such as Aizoanthemum, Aizoon and Gunniopsis may not be monophyletic (C. Klak, pers. comm.). In contrast, phylogenetic relationships of the smallest subfamily, Sesuvioideae, which is sister to the remaining Aizoaceae (Klak & al. 2003a, b), are resolved and generic concepts were clarified recently (Thulin & al. 2012; Bohley & al. 2015).

For Basellaceae, Eriksson (2007) recognized four genera and 19 species in comparison to four genera and 17–22 species accepted by Sperling & Bittrich (1993). In his phylogenetic analysis based on morphological data, three of the genera are supported as monophyletic, while the monophyly of the fourth genus (Basella) is more uncertain. This analysis is well sampled (all taxa), but the resolution is rather poor. No analysis based on molecular data has been done yet.

Available treatments in modern floras are patchy on a global level

Monographic work provides the in-depth synthetic information, and the checklist and gap analysis presented here is aimed at defining part of the baseline for such analysis in the Caryophyllales where it is still missing. However, for the aim of creating a global synthesis of knowledge in the Caryophyllales it is indispensable to consider also the information published in floras.

It is difficult to know in how many floras or related works the Caryophyllales have been treated in the past, especially in regions with a long history of botanical activity such as C and W Europe. In fact, if we take the establishment of the Linnaean classification system and naming as a starting point, we can commence right away in the 18th century, for example with Linnaeus's own Flora suecica (Linné 1745). Flora treatments are numerous; setting aside the numerous works of mostly historical interest, Frodin (2001) in the second edition of “Guide to standard floras of the world” gave information on nearly 1000 general floras distributed in ten major regions of the world. Only in a few cases is there specific information about the families or groups treated in each flora (e.g. Flora of Nigeria: Caryophyllales by Ghazanfar 1991); for the other floras it is necessary to review each flora individually in order to identify works of significance for a global synthesis.

Our approach for uniting the information available for the global synthesis is partly based on taking advantage of information technologies, and fortunately floras are increasingly published on the World Wide Web. An initial review of such publication has revealed that many historical floras that include treatments of Caryophyllales are already available online, for example the pre-1900 floras of the Alps, Australia, Barbados, Brazil, India, Jamaica, Niger, Sri Lanka and Syria, and pre-1990 treatments from Chile, Costa Rica, Fiji, Guatemala, Japan, Madagascar, Panama, South Africa and Taiwan. The bibliographic references of these floras are cited in Frodin (2001), but can also be accessed through the Biodiversity Heritage Library (BHL 2005+), JSTOR (JSTOR 2000+), Gallica (1997+) and Google Books (2015). More recent floras including the Caryophyllales are those from China, Nicaragua, the Malesian region (Indonesia, Malaysia, Singapore, Brunei Darussalam, the Philippines, and Papua New Guinea) and the Zambesi river basin (Botswana, Malawi, Mozambique, Zambia, Zimbabwe and the Caprivi Strip), in which the last treatments for some families of Caryophyllales were printed in the 2000s. Incomplete floras (and incomplete for Caryophyllales so far) treat Argentina, the Hawaiian Islands, North America north of Mexico, the Marquesas Islands, Mesoamerica, Madagascar, the Neotropics, Pakistan, Palestine and Tasmania.

Most of these are simply digitized print treatments (representing images of the actual print work, which, depending on their quality, may or may not be searchable after optical character recognition — OCR). In contrast to this, very few “true” e-floras exist, i.e. floras produced with the online publication as their principal output and making full use of existing biodiversity informatics techniques. An example of the latter is the Flora of Western Australia (Western Australian Herbarium 1998+).

However, increasingly various intermediates between electronic representations of print media and true e-floras are becoming available, partly as a result of the computerized editing process of the print publication, and partly because printed floras are “marked up” in order to database their content, for example the treatments of Flora Malesiana (see Hamann & al. 2014).

Another important source of information on Caryophyllales are checklists, which are mostly available online, because most of them were developed over the past two decades. Some of them refer to taxa treated in previously printed floras, some of them are continuously updated and others are in progress. Such checklists are available for Africa, Argentina, Australia, Bolivia, Botswana, Brazil, central Africa, Cono Sur (Argentina, southern Brazil, Chile, Paraguay and Uruguay), Costa Rica, Croatia, Cyprus, Ecuador, Europe plus the Mediterranean region, Germany, the Guiana Shield (Guyana, Suriname, French Guiana and part of Venezuela), Iran, Ireland, Israel, Lesotho, Madagascar, Mexico, Micronesia, Mongolia, Myanmar, Namibia, Nepal, New Zealand, the pan-Arctic region, Paraguay, Peru, Portugal, the Philippines, Singapore, South Africa, southern Africa, Suriname, Swaziland, Switzerland, Taiwan and the United States.

All of these floristic projects have generated valuable information that has increased our knowledge about the Caryophyllales. An online bibliography of such sources of information focussing on Caryophyllales is in preparation, and we envision using this as the base of a comprehensive gap analysis for the order, and also as the basis for an analysis of regional differences in taxon concepts. It became clear from the preliminary survey that such gaps exist, and that there is a lack of synchronization of taxon concepts, partly due to the state of knowledge at the time of the production of the treatment, but often also caused by a specific local perspective that needs to be placed into a wider geographic context. This was one of the reasons for the decision to use the EDIT Platform for Cybertaxonomy for data management, because this is currently the only taxonomic software system natively supporting different classifications, taxonomic concepts and taxon-concept relationships. It indicates also the need for increased efforts to share and integrate the information generated and to promote the filling of gaps in both geographic and taxonomic coverage. This will be facilitated by the application of information technology, making the information openly available in electronic form and thus furthering the process of future revision and dissemination. Additionally, it enables new kinds of links to current data, including those available only in virtual form, which has not readily been possible in the past (Frodin 2001).

Conclusions and future work

While the published version of this treatment only includes citable publications as its basic reference, there will be a dynamic online version of this generic synopsis that will not only be continuously updated but also become more extensive. To facilitate both interaction in the scientific community and to inspire further research on the Caryophyllales, key data to relevant current projects and research underway will be presented. One of the key steps on the way to a synthesis of Caryophyllales will be identifying specialists who are working at the species level; some of them are those who contributed to this generic synopsis, but others have already been identified and agreed to collaborate. Within the network, we then have to organize the work on taxonomic groups with several specialists and to develop a format, as standardized as possible, for the species-level taxonomic treatments. In addition, directories of specialists, of electronic resources and an online bibliography for the Caryophyllales will be developed. Starting with the Caryophyllales 2015 conference in Berlin (September 2015), regular meetings of the Caryophyllales community will drive this process.

Role of authors

The draft of the generic checklist and the initial data entry was the work of PH, who also provided the treatments of Achatocarphaceae, Agdestidaceae, Ancistrocladeceae, Asteropeiaceae, Barbeuiaceae, Didiereaceae, Dioncophyllaceae, Droseraceae, Drosophyllacae, Frankeniaceae, Halophytaceae, Limeaceae, Lophiocarpaceae, Microteaceae, Nepenthaceae, Nyctaginaceae, Physenaceae, Rhabdodendraceae, Sarcobataceae, Simmondsiaceae and Stegnospermataceae and collaborated in some notes of Chenopodiaceae, Phytolaccaceae and Polygonaceae. The following groups were revised by specific authors: Aizoaceae: CK, with contributions by GK (Sesuvioideae); Amaranthaceae: TB, with contributions by GK (Polycnemoideae); Anacampserotaceae, Molluginaceae and Portulacaceae: GO; Montiaceae and Talinaceae: GO, with contributions by UE; Cactaceae: SA, UE, NK, RN, BOS; Caryophyllaceae: RR, BO (Sileneae), with contributions by SvM; Basellaceae: RE; Chenopodiaceae: HA, HFO, SFB, GK, PU; Gisekiaceae: GK; Plumbaginaceae, Kewaceae, Macarthuriaceae and contributions to other families (e.g. Deeringia, Hypertelis, Microtea): SvM; Polygonaceae: ICN, AS; Tamaricaceae: HA. WGB extensively rechecked the nomenclatural references and standardization of database entries. SvM edited entries and updated the database. Introduction and summary were prepared as a draft by PH, TB and WGB. Comments from co-authors were incorporated, and the final text edited by WGB, SvM, NK and TB.

Acknowledgements

We would like to acknowledge the technical support by Katja Luther, Andreas Müller and Cherian Mathew at the BGBM during work with the EDIT Platform software and the production of the generic list directly from the database. There was a productive exchange with James Solomon (Missouri Botanical Garden) while checking our nomenclatural data against the Tropicos database. Werner Greuter, Nicholas Turland, and Wolf-Henning Kusber are acknowledged for advice on complicated cases of nomenclature. Demet Töre provided literature on Plumbaginaceae.

Wilhelm Barthlott, Peter Bruyns and Nicholas Turland are thanked for granting permission to use their photographs. David Hunt, John McNeill, Sergei Mosyakin, Kai Müller, Louis Ronse de Craene, Nigel Taylor and one anonymous reviewer are thanked for their valuable comments on an earlier version of the manuscript.

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